PROCESS OF PRODUCING A FUEL STREAM COMPRISING RENEWABLE CARBON

Description

FIELD

The field is the process of producing a fuel stream comprising renewable carbon. The field may particularly relate to the processing of a mineral feed and a renewable feed to produce a fuel stream.

BACKGROUND

Biomass refining or biorefining is becoming more prevalent in industry. Cellulose fibers and sugars, hemicellulose sugars, lignin, syngas, and derivatives of these intermediates are being used by many stakeholders for chemical and fuel production. They are capable of processing incoming biomass much the same as petroleum refineries now process crude oil. Underutilized lignocellulosic biomass feedstocks have the potential to be much cheaper than petroleum, on a carbon basis, as well as much better from an environmental life-cycle standpoint.

Lignocellulosic biomass is the most abundant renewable material on the planet. The lignocellulosic biomass is a potential feedstock for producing chemicals, fuels, and materials. Lignocellulosic biomass normally comprises primarily cellulose, hemicellulose, and lignin. Cellulose and hemicellulose are natural polymers of sugars, and lignin is an aromatic/aliphatic hydrocarbon polymer reinforcing the entire biomass network. Some forms of biomass (e.g., recycled materials) do not contain hemicellulose.

It is beneficial to process biomass in a way that effectively separates the major fractions (cellulose, hemicellulose, and lignin) from each other. Cellulose from biomass can be used in industrial cellulose applications directly, such as to make paper or other pulp-derived products. The cellulose can also be subjected to further processing to either modify the cellulose in some way or convert it into glucose. Hemicellulose sugars can be fermented to a variety of products, such as ethanol, or converted to other chemicals. Lignin from biomass has value as a solid fuel and also as an energy feedstock to produce liquid fuels, synthesis gas, or hydrogen; and as an intermediate to make a variety of polymeric compounds. Additionally, minor components such as proteins or rare sugars can be extracted and purified for specialty applications.

Great importance has been attached to renewable energy resources all over the world. Biomass derived ethanol fuel is becoming a member of the technical field of liquid fuel, and the processes of producing ethanol fuel from starch and cellulose are under modification and improvement. The use of lignocellulosic biomass as a source of renewable raw material is a leading area for the replacement of petroleum products.

Bioethanol can be produced by fermentation of biological feedstock. Fermentation produces substantial carbon dioxide which must be managed. The bioethanol is then dehydrated to produce ethylene.

Ethylene can be dimerized into olefins such as C4, C6 and C8 olefins. Olefin oligomerization is a process that can oligomerize smaller olefins into larger olefins. More specifically, it can convert olefins into distillates including jet fuel and diesel range products. The olefinic oligomerized distillate can be hydrogenated for use as transportation fuel.

An ethanol to jet fuel process is one of the routes that holds promise to minimize or eliminate net carbon combustion. The end product of this process is jet and diesel fuel produced out of bioethanol. Jet fuel is a sustainable aviation fuel intended to replace jet fuel produced out of conventional sources such as crude oil.

Jet fuel is one of the few petroleum fuels that cannot be replaced easily by electrical motor systems because a high energy output is required to fuel planes which cannot be supplied with electric motors. Large incentives are currently available for green jet fuel in certain regions to reduce the environmental impact of fossil-derived jet fuels.

Currently, a limited supply of lignin is available as a by-product of the pulp and paper industry. However, in the near future, large quantities of lignin residue material will be available from biomass-to-ethanol processes and other biorefineries and associated processes. So far, in typical biorefinery process designs, lignin appears as a residual material with limited opportunities for its utilization. Other sources of lignin material can include agricultural products and wastes, municipal wastes, and the like.

Low carbon intensive sustainable aviation fuels are the need of the hour to reduce aviation greenhouse gas emissions. It would also help to minimize dependence on fossil fuels and volumetrically enhance the drop in aviation fuel share by the biomass derived jet fuels. Furthermore, existing routes to produce SAF are cost intensive and feedstock limited.

Further, many governments are promoting the use of biofuels as a replacement for mineral feed based fuels. A biofuel will not necessarily produce less carbon than mineral feed based fuel when it is burnt, but since such fuels are typically derived from newly-grown plants or animal products, and since those plants and animals will have absorbed atmospheric carbon directly or indirectly throughout their life, the net carbon output of the fuel can be greatly reduced.

In the US and European markets, suppliers are already required to add a proportion of biofuel to various grades of mineral feed based fuels. In the UK for example, under the Renewable Transport Fuels Obligation, suppliers of fossil fuels must ensure that a specified percentage of the road fuels they supply is made up of renewable fuels.

There is a need for a blended fuel comprising the biofuel for addressing the rising demand and mandate towards reducing the carbon emissions.

BRIEF SUMMARY

The present disclosure provides a process of producing a fuel stream comprising renewable carbon is disclosed. The process comprises producing an olefinic stream or an alcohol stream from a renewable feedstock. An aromatic stream and an alkylating agent comprising the olefinic stream or the alcohol stream is charged to an alkylation reactor to alkylate the aromatic stream with the alkylating agent to produce an alkylated aromatic product stream. The alkylated aromatic product stream comprises about 0.1 wt % to about 67 wt % renewable carbon. The present disclosure provides a solution to refiners to produce a fuel stream that meets the blending target of the renewable fuel. One or more blended fuels may be produced from the current process. The fuel stream of the present process may comprise about 0.1 wt % to about 67 wt % renewable carbon.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic drawing of a process of producing jet fuel in accordance with an embodiment of the present disclosure.

FIG. 2 is a schematic drawing of an exemplary embodiment of processing a biomass feed in accordance with the process of producing jet fuel of the present disclosure.

FIG. 3 is a graph showing A9+ aromatics concentration at various reactor inlet temperatures and recycle mass flow rates over time.

DEFINITIONS

The term “communication” means that fluid flow is operatively permitted between enumerated components, which may be characterized as “fluid communication”.

The term “downstream communication” means that at least a portion of fluid flowing to the subject in downstream communication may operatively flow from the object with which it fluidly communicates.

The term “upstream communication” means that at least a portion of the fluid flowing from the subject in upstream communication may operatively flow to the object with which it fluidly communicates.

The term “direct communication” means that fluid flow from the upstream component enters the downstream component without passing through any other intervening vessel.

The term “indirect communication” means that fluid flow from the upstream component enters the downstream component after passing through an intervening vessel.

The term “bypass” means that the object is out of downstream communication with a bypassing subject at least to the extent of bypassing.

As used herein, the term “predominant” or “predominate” means greater than 50%, suitably greater than 75% and preferably greater than 90%.

The term “column” means a distillation column or columns for separating one or more components of different volatilities. Unless otherwise indicated, each column includes a condenser on an overhead of the column to condense and reflux a portion of an overhead stream back to the top of the column and a reboiler at a bottom of the column to vaporize and send a portion of a bottoms stream back to the bottom of the column. Feeds to the columns may be preheated. The top pressure is the pressure of the overhead vapor at the vapor outlet of the column. The bottom temperature is the liquid bottom outlet temperature. Overhead lines and bottoms lines refer to the net lines from the column downstream of any reflux or reboil to the column. Stripper columns may omit a reboiler at a bottom of the column and instead provide heating requirements and separation impetus from a fluidized inert media such as steam. Stripping columns typically feed a top tray and take main product from the bottom.

As used herein, the term “separator” means a vessel which has an inlet and at least an overhead vapor outlet and a bottoms liquid outlet and may also have an aqueous stream outlet from a boot. A flash drum is a type of separator which may be in downstream communication with a separator that may be operated at higher pressure. As used herein, the term “boiling point temperature” means atmospheric equivalent boiling point (AEBP) as calculated from the observed boiling temperature and the distillation pressure, as calculated using the equations furnished in ASTM D1160 appendix A7 entitled “Practice for Converting Observed Vapor Temperatures to Atmospheric Equivalent Temperatures”.

As used herein, the term “True Boiling Point” (TBP) means a test method for determining the boiling point of a material which corresponds to ASTM D-2892 for the production of a liquefied gas, distillate fractions, and residuum of standardized quality on which analytical data can be obtained, and the determination of yields of the above fractions by both mass and volume from which a graph of temperature versus mass % distilled is produced using fifteen theoretical plates in a column with a 5:1 reflux ratio.

As used herein, the term “T5”, “T90” or “T95” means the temperature at which 5 mass percent, 90 mass percent or 95 mass percent, as the case may be, respectively, of the sample boils using ASTM D-86 or TBP.

As used herein, the term “initial boiling point” (IBP) means the temperature at which the sample begins to boil using ASTM D-7169, ASTM D-86 or TBP, as the case may be.

As used herein, the term “end point” (EP) means the temperature at which the sample has all boiled off using ASTM D-7169, ASTM D-86 or TBP, as the case may be.

As used herein, the term “diesel” means hydrocarbons boiling in the range of an IBP between about 125° C. (257° F.) and about 175° C. (347° F.) or a T5 between about 150° C. (302° F.) and about 200° C. (392° F.) and the “diesel cut point” comprising a T95 between about 343° C. (650° F.) and about 399° C. (750° F.) using the TBP distillation method or a T90 between 280° C. (536° F.) and about 340° C. (644° F.) using ASTM D-86. The term “green diesel” means diesel comprising hydrocarbons not sourced from fossil fuels.

As used herein, the term “jet fuel” means hydrocarbons boiling in the range of a T10 between about 190° C. (374° F.) and about 215° C. (419° F.) and an end point of between about 290° C. (554° F.) and about 310° C. (590° F.). The term “green jet fuel” means jet fuel comprising hydrocarbons not sourced from fossil fuels.

As used herein, the term “Biofuel,” means a fuel product at least partly derived from “biomass,” the latter being a renewable resource of biological origin.

As used herein, the term “Lignin,” means a complex chemical compound most commonly derived from wood and generally being an integral part of the secondary cell walls of plants.

As used herein, the term “Cellulose,” means essentially a glucose polymer by virtue of it being a linear polysaccharide comprised of from hundreds to thousands of D-glucose monomeric units linked via glycosidic bonds.

As used herein, the term “Hemicellulose,” means any of several heteropolysaccharides present in almost all plant cell walls along with cellulose. In contrast to cellulose, hemicellulose is commonly branched, typically shorter in length/molecular weight (a few hundred to a few thousand saccharide units), and contains many different sugar monomers such as, but not limited to, glucose, xylose, mannose, galactose, rhamnose, and arabinose.

As used herein, the term “lignocellulosic,” means plant biomass that is composed of cellulose, hemicellulose, and lignin.

As used herein, the term “Generation 2 (Gen 2) biofuel,” means any biofuel whose production is independent of the food chain.

DETAILED DESCRIPTION

Turning to FIG. 1, an embodiment of a process 101 for producing a fuel stream comprising renewable carbon is disclosed. The process 101 may comprise an alkylation unit 150, and a hydrotreating unit 157. An aromatic stream in line 142 may be charged to the alkylation unit 150. The aromatic stream in line 142 may be produced from a mineral feed or a fossil-based feed. In an embodiment, the aromatic stream in line 142 may comprise at least one of a reformate stream, a naphtha stream, a kerosene stream, a diesel stream, and a light cycle oil stream. In the alkylation unit 150, the aromatic stream in line 142 may be alkylated with an alkylating agent to produce an alkylated aromatic product stream. An alkyl agent stream in line 112 may be passed to the alkylation unit 150. In accordance with an exemplary embodiment, the alkylating agent may be produced from a renewable feedstock. In an embodiment, the alkylating agent may comprise at least one of an olefinic stream and an alcohol stream produced from the renewable feedstock.

In an exemplary embodiment, the alcohol stream in line 112 may comprise at least one of methanol, ethanol, iso-butanol, and propanol.

In accordance with the present disclosure, the methanol may be produced from carbon oxides. Syngas is defined as a gas comprising primarily carbon oxides including carbon monoxide (CO), and carbon dioxide (CO2), and hydrogen (H2). Optionally, syngas may also include methane (CH4), and small amounts of ethane and propane. Conventional processes for converting carbon components to syngas include steam reforming, partial oxidation, autothermal reforming, and combinations of these processes. The hydrogen gas stream may be taken from any suitable sources. In an aspect, the hydrogen gas stream may be produced by a water electrolysis unit. In an exemplary embodiment, the water electrolysis unit may be powered by green energy. In the water electrolysis unit, the water is split into the oxygen and hydrogen. The hydrogen stream may be combined with a carbon dioxide stream to provide a syngas stream which is charged to a methanol synthesis section. Alternatively, the hydrogen stream and the carbon dioxide stream may be charged separately to the methanol synthesis section.

The methanol synthesis section may comprise more than one methanol converter. The hydrogen stream and the carbon dioxide stream may be charged to a methanol converter. Perhaps, the hydrogen stream and the carbon dioxide stream may be passed to a booster compressor to provide a compressed syngas stream before passing to the methanol converter. The compressed syngas stream may be heated and passed to the methanol converter where it is converted to a methanol composition. The methanol synthesis process is accomplished in the presence of a methanol synthesis catalyst.

A suitable methanol synthesis catalyst may be a copper on a zinc oxide and alumina support. Synthesis conditions of the methanol converter may include a temperature of about 200 to about 300° C. and a pressure of about 3.5 to about 10 MPa. Reaction equilibrium typically requires methanol separation and recycle of unreacted reagents to the synthesis reaction to obtain sufficient conversion. The methanol synthesis reaction is highly exothermic. A boiler feed water (BFW) is passed to the methanol converter to generate a steam stream, which is withdrawn from the methanol converter. The generation of steam absorbs the exotherm in the methanol synthesis reaction.

The reactor effluent stream of the methanol converter may be cooled and separated in a gas-liquid separator 150 to provide a vapor stream and a liquid stream. The vapor stream and the liquid stream may be further processed to recover methanol. The vapor stream may comprise carbon dioxide that has not yet converted to methanol. The vapor stream may be charged to a second methanol converter to produce methanol.

In aspect, a methanol stream may be discharged from the methanol synthesis section and charged to the alkylation unit 150 in the alkylating agent stream in line 112.

In an embodiment, the alcohol stream in line 112 may comprise ethanol produced from a lignocellulosic biomass feed stream. Cellulosic biomass may be defined as biomass containing cellulose. Here, biomass refers to substances having their edible parts removed but still rich in biomass energy, such as crop straw, bamboo, reed, trees, leaves, weeds and hydrophytes, etc. The main constituents of such cellulosic biomass may include polysaccharide celluloses, hemicelluloses, and lignin of polyaromatic compounds. Lignocellulosic biomass is essentially a source of carbohydrates. It is composed of three main constituents: cellulose, hemicellulose, and lignin. Hemicellulose is a polysaccharide essentially consisting of pentoses and hexoses. Lignin is a macromolecule of complex structure and high molecular weight, composed of aromatic alcohols connected by ether bonds. The three basic building blocks of lignin, p-coumaryl alcohol, coniferyl alcohol, and sinapyl alcohol, are synthesized via the phenylpropanoid pathway in plants and differ in their extent of methoxylation (0, 1, and 2, respectively). Lignin is synthesized via enzymatic dehydrogenation of these monomers, which form both C—O and C—C bonds, leading to a heterogeneous structure and a three-dimensional structure.

Cellulose and lignin represent two of the most prominent renewable carbon sources. Lignin, a second to cellulose as the most plentiful renewable carbon source on earth, is an amorphous three-dimensional energy-rich phenolic biopolymer, which is deposited in all vascular plants and provides rigidity and strength to their cell walls. The lignin polymeric structure is composed primarily of three phenylpropanoid building units: p-hydroxyphenylpropane, guaiacylpropane, and syringylpropane interconnected by etheric and carbon-to-carbon linkages. Generally, in unprocessed lignin, two thirds or more of these linkages are ether bonds, while the remaining linkages are carbon-carbon bonds.

Different types of lignin differ significantly in the ratio between these monomers. Inherent in its molecular nature, the lignin bio-mass component can potentially be converted directly to liquid fuels, for example high-octane alkylbenzene, aromatic ether gasoline-blending components, and/or naphthenic kerosene fuels (NK).

For ethanol production, the lignocellulosic biomass feed stream may be passed to a biomass processing unit to separate lignin from the biomass. In the biomass processing unit, lignocellulosic biomass feed stream undergoes multiple processing steps to yield alcohol and lignin. These processing steps may primarily comprise hydrolysis, followed by fermentation and distillation that finally results in ethanol and lignin.

In an exemplary embodiment, the lignocellulosic biomass may be subjected to a chemical pre-treatment step in the biomass processing unit. Some “pretreatment” of the biomass may be carried out prior to attempting the enzymatic hydrolysis of the cellulose and hemicellulose in the biomass. Pretreatment refers to a process that converts lignocellulosic biomass from its native form, in which it is resistant to cellulase enzyme systems, into a form for which cellulose hydrolysis is effective. Compared to untreated biomass, effectively pretreated lignocellulosic materials may be characterized by an increased surface area (porosity) accessible to cellulase enzymes, and solubilization or redistribution of lignin. Increased porosity results mainly from a combination of disruption of cellulose crystallinity, hemicellulose disruption/solubilization, and lignin redistribution and/or solubilization. The relative effectiveness in accomplishing at least some of these factors differs greatly among different existing pretreatment processes.

The purpose of the pretreatment is to significantly disrupt the structure of biomass in order to: (a) reduce the crystallinity of cellulose, (b) increase accessibility/susceptibility of cellulose and hemicellulose chains to enzymes/catalysts by increasing the surface area/porosity and (c) remove lignin. Thermo-chemical biomass pretreatments techniques may be used for improving the digestibility of this highly recalcitrant biomass. These pretreatments may include dilute acid contact, steam explosion, hydrothermal pyrolysis, dissolution in organic solvents in an aqueous medium, ammonia fiber explosion, contact with strong alkali using a base such as ammonia, sodium hydroxide or lime), and highly concentrated phosphoric acid contact.

In lime pretreatment, the biomass is pretreated with calcium hydroxide and water under different conditions of temperature and pressure. It can be conducted via (i) short-term pretreatment that lasts up to 6 hours, requiring temperatures of about 100° C. to about 160° C.

In some embodiments, the lignocellulosic biomass may be mixed with an ionic liquid for a sufficient time and temperature to swell the lignocellulosic biomass without dissolving the lignocellulosic biomass in the ionic liquid, and treating the swelled lignocellulosic biomass under mild alkaline treatment to separate the lignin from the cellulose and hemicellulose.

After pretreatment, the separated lignin may be subjected to a high-temperature hydrolysis so as to reduce oxygen content of the lignin and provide a lignin rich stream. By reducing the oxygen content of the lignin, the lignin becomes more amenable to hydroprocessing because, for example, less hydrogen is needed. Following hydrolysis, the processed lignin can be hydroprocessed to form usable products such as biofuel. In an exemplary embodiment, the hydrolysis of the lignin may be carried out at a temperature of about 220° C. to about 300° C. The lignin-rich stream obtained after the hydrolysis step may have an oxygen content of not more than 25 weight percent on an ash-free basis.

In another embodiment, lignin may be separated from the biomass by chemical delignification by separating the lignin from the cellulose.

The lignin-rich stream may be fermented to produce alcohol. An exemplary embodiment of the biomass processing unit and the related steps is disclosed in FIG. 2 and described herein below.

Any renewable material that can provide saccharides may be used as a feed for the biomass processing unit 110 in FIG. 2. In this case, corn, the most prevalent renewable for making alcohol, is exemplified. In a typical process, shelled corn is delivered with debris removed and stored in a storage silo 12. Corn is conveyed from the silo to a weigh tank 14 and a series of separators 16 and 17. The separated corn kernels are transported to a dry destoner 18 to remove grit and stones and conveyed to a hammer mill 20. In the hammer mill corn kernels are ground to flour and collected in a flour bin 22.

The corn flour is conveyed from the bin 22 to a slurry tank 24 in which it is mixed with an enzyme such as alpha amylase from line 25 and aqueous lime from line 26. Alpha-amylase is an enzyme that catalyzes the hydrolysis of α-bonds of large, α-linked polysaccharides, such as starch and glycogen, yielding shorter chains thereof, dextrins, and maltose. The lime is added usually in the form of calcium hydroxide to disrupt the lignocellulosic matrix to make the substrate more accessible to the enzymes. The slurried mixture is conveyed after a short residence time such as 3 to 10 minutes and heated to about 70 to about 90° C. en route to a liquefaction tank 28.

The liquefaction tank 28 is heated by a steam jacket to maintain temperature of about 70 to about 90° C. Residence time is optimized to reduce formation of dextrin units which are not fermentable in yeast. The multistirred liquefaction tank retains the slurry from about 45 to about 75 minutes. The enzyme breaks the starch into soluble simpler starches, glucose and dextrose in a mash.

The mash is conveyed to one or more cooking kettles 30, 31 where heating continues by a steam jacket at a temperature of about 100 to about 120° C. while continually stirring. Sulfuric acid from line 32 may be added to the cooking kettles 30, 31 to break up and loosen any polymeric material such as lignin and cellulose. Residence time in the cooking kettles 30, 31 may be for about 10 to about 20 minutes to mitigate by-product formation of methanol and fusel oils. The cooked mash is cooled to between about 50 and about 70° C. and conveyed to the saccharification tanks 34, 35.

Enzyme such as glucoamylase is added to the saccharification tanks from line 36 to effect saccharification of the cooked mash at the reduced temperature under stirring to produce dextrin. Residence time in the saccharification tanks 34, 35 is about 1.5 to about 2.5 hours. Saccharified broth is cooled to about 30 to about 50° C. and conveyed to fermenters 38, 39.

Nutrients in line 40 and anti-foaming agent in line 41 are also added to the fermenter 38. Air in line 42 is added to the bottom of the fermenters 38, 39 to promote ethanol production. Carbon dioxide from line 44 may also be added to the fermenters 38, 39 to promote further agitation in the fermenters. Carbon dioxide is also generated in the fermenters 38, 39. Some of the carbon dioxide is recycled in line 44 to the fermenters while surplus carbon dioxide is taken in line 46.

A beer alcohol stream in line 43 from the fermenters 38, 39 may be fed to a fractionation column 50 to concentrate the alcohol in the overhead line 51. The overhead stream in lien 15 may comprise ethanol. A portion or all of the alcohol in the overhead line 51 may be taken as alkylating agent in line 112 of FIG. 1. The fractionated overhead stream may be condensed with a net vaporous alcohol stream provided from the receiver in a receiver overhead line 52. The condensed overhead stream may be refluxed to the column. Alternatively, the overhead stream in line 51 may be completely condensed with a portion of the condensed stream taken to a rectifier column to further concentrate the alcohol stream. A bottoms stream in line 54 has a portion reboiled and returned to the column while a net bottoms stream comprising solids in non-volatile liquids is taken in line 55. The net bottoms stream in line 55 may contain the lignin. The fractionation column 50 may be operated at around atmospheric pressure with an overhead temperature of about 60° C. (140° F.) to about 90° C. (194° F.) and a bottom temperature of about 90° C. (194° F.) to about 110° C. (230° F.). Lignin is separated in the non-volatile liquids taken in line 55.

In another embodiment, the alcohol stream in line 112 may comprise propanol produced from glycerol. Glycerol hydrogenolysis process converts glycerol into propylene glycol. Glycerol containing feeds that include fatty acids—such as bio-based glycerol feeds—must be pretreated in pretreatment section. Pretreatment section includes combining the fatty acid containing glycerol feed with an acid, such as sulfuric acid or hydrochloric acid, to form an acidulated glycerol feed. The term “acidulated” refers to an acidulated glycerol feed that will contain impurities—other than fatty acids—found in common crude glycerol streams derived from bio-based and other processes. Such impurities can include one or more of methanol, sodium, potassium, tramp impurities, sulfur, iron, nickel, and chloride. Other glycerol feeds such a technical grade glycerol, USP glycerol, technical glycerol and acidulated glycerol can bypass pretreatment section because they do not contain fatty acids.

Glycerol feed stream may be any type of pretreated glycerol feed that has a substantially reduced fatty acid content and, therefore, does not require pretreatment in pretreatment section. Fatty acid free glycerol is generally readily available in several grades: pharmaceutical (USP), food additive grade, and technical grade (industrial). Bio-based glycerol that has not been purified is known as crude glycerin. It is common to remove impurities from crude glycerol by vacuum distillation to form a vacuum distilled crude glycerol. However, the processes of this invention do not require vacuum distilled crude glycerol. Instead, splitter's crude glycerol, an 85% glycerin grade recovered and concentrated from the water of hydrolysis; also known as hydrolyzer crude glycerin, or acidulated glycerol are useful feeds. Soap lye crude could also be used as long as the fatty acids are removed; and an ester crude could be used which is produced from the transesterification of vegetable oils.

Glycerol feed stream may also include methanol as a byproduct of bio-based processes.

An aqueous base feed is also used in the glycerol hydrogenolysis process. Any base that would be understood by one skilled in the art to be useful for adjusting the pH of the chosen glycerol feed to the desired basic pH may be used. The aqueous bases will typically be selected from those that meet one or more criteria of ready availability; little detrimental impact on catalyst activity; inexpensive; and that avoid corrosion issues. Examples of some useful bases are aqueous solutions of NaOH, KOH, ammonium hydroxide, other alkali metal hydroxides, alkoxides and so forth with NaOH and KOH being preferred. The amount of base in the base feed will typically range from about 0.5 to about 5.0 wt % depending upon the base chosen. If the pH is adjusted with NaOH, the concentration of NaOH in the aqueous solution will be from about 0.1 to about 5.0 wt %, and preferably from about 0.5 to about 1.5 wt %. If KOH is the chosen aqueous base, then the concentration of a preferred aqueous solution of KOH will be from about 0.5 to about 2.0 wt %.

The glycerol feed stream and the aqueous base feed is passed to a feed blending section. Feed blending section includes at least a pH adjustment step where the base feed is combined with glycerol feed stream and/or to form a basic glycerol feed stream having the target pH. Feed blending section can optionally include a solid liquid separation step. Feed blending section may be any type of unit operation that effectively admixes two or more miscible liquids. One example of a feed blending section is an inline mixing apparatus in which the liquid feed ingredients are directed and admixed with one another to form the basic glycerol feed. Alternatively, feed blending section may be a surge tank in which the feed ingredients are combined in a controlled manner in order to carefully control the pH of basic glycerol feed. The basic glycerol feed exiting feed blending section will have a basic pH. More preferably the basic glycerol feed will have a pH of from about 10 to 12 and most preferably a pH of about 12.

The basic glycerol feed may be directed to a reaction section which may include a fixed bed catalyst reactor. The basic glycerol feed may be combine with a hydrogen stream, heated and charged to the reactor which operates at glycerol conversion conditions of pressure, temperature and space velocity to form a hydrogenolysis reaction product stream that includes propylene glycol. Any catalyst that is known to be useful in converting glycerol to propylene glycol in the presence of hydrogen may be used in reaction section. Examples of useful catalysts include copper/chromite; copper zinc and copper oxide with BaO, MgO, CaO, and Mo as additives for activity or stability; mixtures of cobalt, copper, manganese and molybdenum. More preferred catalysts are heterogeneous catalysts such as CoPdRe or NiRe on a solid support such as carbon wherein the metals are reduced.

Reactor product stream is directed to gas/liquid separator to form a high pressure separator liquid product which is directed to purification section. The design of purification section is dependent on the purity of the propylene glycol product produced in the reactor section. The first step of product purification is to remove the water and the C1-C3 alcohols. The alcohols are recovered from the water in a fractionation column. The mixed alcohol stream is recovered and contains less than about 10% water and preferably less than about 3% water. A propanol containing stream may be discharged from the purification section and charged to the alkylation unit 150 in the alkylating agent stream in line 112.

In an embodiment, the alcohol stream in line 112 may comprise isobutanol. Isobutanol may be produced from syngas. In an aspect, the syngas may be produced from gasification of biomass and/or municipal solid waste. The syngas stream may be passed through a reaction zone at high temperatures and high pressures in the presence of heterogeneous catalysts. The reaction temperature could range from about 200 to about 450° C., or from about 250 to about 350° C. The pressure could range from about 10 to about 200 atm (1.0 to 20.3 MPa), or from about 50 to about 150 atm (5.1 to 15.2 MPa). In addition to carbon monoxide and hydrogen, carbon dioxide or inert gas, such as nitrogen and argon, may also be present in the syngas.

In the reaction zone, methanol, substantial amounts of ethanol and propanol, and possibly a small amount of isobutanol are formed directly from the syngas on some heterogeneous catalysts. The catalysts could include, but not limited to, copper—cobalt containing catalysts, copper—iron containing catalysts, copper—nickel containing catalysts, promoted molybdenum catalysts (e.g., molybdenum trioxide, molybdenum disulfide, molybdenum phosphide and molybdenum carbide) and precious metal catalysts (e.g., rhodium), and combinations thereof.

The effluent from the reaction zone may be sent to a separation zone where it is separated into an ethanol and isobutanol containing stream. This stream may be combined with another syngas stream to form a combined stream and sent to a second reaction zone. The ethanol and propanol react with the syngas in the presence of heterogeneous catalysts in the second reaction zone to produce isobutanol. The catalysts could include, but are not limited to, the aforementioned direct isobutanol synthesis catalysts, such as alkali and alkaline earth promoted ZnO or CuO catalysts. The reaction temperature could be from about 200 to about 500° C., preferably from about 250 to about 450° C. The pressure could be from about 10 (1.01 MPa) to about 300 atm (30.4 MPa), or from about 50 (5.1 MPa) to about 200 atm (20.3 MPa).

The reactor effluent stream from the second reaction zone may be passed to a product recovery section to recover an isobutanol stream. In aspect, an isobutanol stream may be discharged from the product recovery section and charged to the alkylation unit 150 in the alkylating agent stream in line 112.

In another aspect, the alkylating agent stream in line 112 may comprise an olefinic stream. In an embodiment, the olefinic stream in line 112 may comprise any olefinic stream having C2 to C5 olefins. In accordance with the present disclosure, the olefinic stream may be taken from an methanol to olefins unit, a paraffin dehydrogenation unit, a steam cracking unit, or an alcohol dehydration unit.

Referring back to the alkylation unit 150, the alkylating agent stream in line 112 may be combined with the aromatic stream in line 142 to provide an alkylation charge stream in line 144 which is passed to the alkylation unit 150. The aromatic stream in line 142 may comprise benzene, toluene, and xylene (BTX). In an embodiment, the aromatic stream in line 142 may be a BTX rich stream. In an aspect, the alkylation charge stream in line 144 may comprise a molar ratio of the alkylating agent in line 112 to the aromatic stream in line 142 from about 0.1 to about 6, preferably from about 0.1 to about 4. In an exemplary embodiment, the alkylation charge stream in line 144 may comprise a molar ratio of the alkylating agent in line 112 to the BTX in line 142 from about 0.1 to about 6, preferably from about 0.1 to about 4.

Alkylation involves transfer of an alkyl group from an alkylating agent to an aromatic substrate widely referred to as an electrophilic aromatic substitution reaction. In the alkylation unit 150, C6+ alkylaromatics are produced by catalytically reacting the aromatic stream with the alkylating agent in the presence of an alkylation catalyst at an alkylation temperature and alkylation pressure to produce a product stream comprising C6+ alkylaromatics. The alkylation reaction is conducted at a temperature where the thermodynamics are favorable. In an embodiment, the alkylation unit 150 may be operated at a temperature of about 50° C. to about 400° C. and a pressure of about 1000 kPa (10 bar) to 10000 kPa (100 bar). Weight hourly space velocity (WHSV) for the alkylation reactor may range from about 0.1 hr⁻¹ to about 10 hr⁻¹. When an alcohol is the alkylation agent, water is produced and removed from the alkylation unit 150.

In an aspect, the alkylation catalyst may comprise one or more from the group comprising sulfuric acid, hydrofluoric acid, aluminum chloride, boron trifluoride, solid phosphoric acid, chlorided alumina, acidic alumina, aluminum phosphate, silica-alumina phosphate, amorphous silica-alumina, aluminosilicate, aluminosilicate zeolite, zirconia, sulfated zirconia, tungstated zirconia, tungsten carbide, molybdenum carbide, titania, sulfated carbon, phosphated carbon, phosphated silica, phosphated alumina, acidic resin, heteropolyacid, inorganic acid, and a combination of any two or more of the foregoing.

In one embodiment, the alkylation catalyst comprises an aluminosilicate zeolite. In one version, the alkylation catalyst further comprises a modifier selected from the group consisting of Ga, In, Zn, Fe, Mo, Ag, Au, Ni, P, Sc, Y, Ta, a lanthanide, and a combination of any two or more of the foregoing. In another version, the alkylation catalyst further comprises a metal selected from the group consisting of Cu, Ag, Au, Pt, Ni, Fe, Co, Ru, Zn, Cd, Ga, In, Rh, Pd, Ir, Re, Mn, Cr, Mo, W, Sn, Os, an alloy of any two or more of the foregoing, and a combination of any two or more of the foregoing.

In an embodiment, the alkylation catalyst may be selected from zeolite catalyst or ionic liquid catalyst. In an exemplary embodiment, the alkylation catalyst comprises a SAPO based catalyst.

An alkylated aromatic product stream comprising a liquid fuel is discharged from the alkylation unit 150 in line 152. In accordance with the present disclosure, the alkylated aromatic product stream in line 152 can be used as a biofuel or a motor biofuel.

In an embodiment, a portion of the alkylated aromatic product stream may be taken in a recycle stream in line 154. The recycle stream in line 154 may be recycled back to the alkylation unit 150. In an exemplary, the recycle stream in line 154 may be recycled to the alkylation unit 150 at a combined feed ratio (CFR) of about 1 to about 5. The “combined feed ratio” (or CFR) may be defined as a ratio of a sum of mass flow rate of the alkylation charge stream in line 144 and a mass flow rate of the recycle stream in line 154 to a mass flow rate the combined stream in line 144. Typically, the alkylation substrate is recycled because the alkylating agent is stoichiometrically deprived.

The remaining alkylated aromatic product stream is taken in line 153. In an aspect, the alkylated aromatic product stream in line 153 may be passed to an optional treatment unit 157. In an embodiment, the alkylated aromatic product stream in line 153 may be split into a first alkylated aromatic product stream in line 155 and a second alkylated aromatic product stream in line 156. The second alkylated aromatic product stream in line 156 may be charged to the treatment unit 157. The first alkylated aromatic product stream in line 155 may bypass the treatment unit 157. In an exemplary embodiment, the treatment unit 157 is a hydrotreating unit. In the hydrotreating unit 157, the second alkylated aromatic product stream in line 156 may react with hydrogen to yield one or more hydroprocessed or hydrotreated products. Such a hydrotreating step may itself comprise multiple sub-steps. In the hydrotreating unit 157, the second alkylated aromatic product stream in line 156 may be contacted with a hydrotreating catalyst in a hydrogen environment. The hydrotreating catalyst may comprise an active metal or metal-alloy hydrotreating catalyst component that is operationally integrated with a refractory support material. In some embodiments, the active metal catalyst component may be selected from the group consisting of cobalt-molybdenum (Co—Mo) catalyst, nickel-molybdenum (Ni—Mo) catalyst, noble metal catalyst, and combinations thereof. In some embodiments, the refractory support material typically comprises a refractory oxide support such as, but not limited to, Al₂O₃, SiO₂—Al₂O₃, and combinations thereof. In some embodiments, the hydrotreating step may use an alumina-supported nickel-molybdenum catalyst. A zeolite including silico-aluminophosphate (SAPO) catalyst can be used. The hydrotreating step may be carried out at a temperature from about 288° C. (550° F.) to about 427° C. (800° F.), preferably between about 349° C. (690° F.) and about 400° C. (752° F.) and a pressure of about 700 kPa (g) (100 psig) to about 21 MPa (g) (3000 psig). In some such embodiments, the hydrotreating is carried out under a hydrogen partial pressure of between about 400 psig and about 2000 psig. In some or other such embodiments, the hydrotreating may be carried out under a hydrogen partial pressure of between about 3447 kPa (g) (500 psig) and about 10342 kPa (g) (1500 psig).

The hydrotreating catalyst in the hydrotreating unit 157 may comprise one or more noble metals dispersed on a high surface area support. Non-limiting examples of noble metals include platinum and/or palladium dispersed on an alumina support such as gamma-alumina. Suitable hydrotreating catalysts may include BDO 200, BDO 300 or BDO 400 available from UOP LLC in Des Plaines, Illinois.

In the hydrotreating unit 157, the aromatic rich second alkylated aromatic product stream in line 156 may be contacted with a hydrotreating catalyst in the presence of hydrogen at hydrotreating conditions. The hydrotreating catalyst catalyzes hydrodeoxygenation reactions, including hydrodecarboxylation and hydrodecarbonylation reactions, to remove oxygenate functional groups which may be converted to water and carbon oxides.

In an embodiment, the second alkylated aromatic product stream in line 156 may be hydrodeoxygenated in the hydrotreating unit 157 before it is separated into one or more liquid fuels. In an aspect, the second alkylated aromatic product stream in line 156 may undergo catalytic hydrogenation in the hydrotreating unit 157. In hydrotreating unit 157, second alkylated aromatic product stream in line 156 may be catalytically reacted with hydrogen in a hydrogenation reactor in the presence of a supported hydrogenation catalyst to produce a hydrogenated effluent stream. The hydrogenation reactor may be operated at a temperature of about 50° C. to about 400° C. and a pressure of about 980 kPa (g) to about 9810 kPa (g). In an exemplary embodiment, the hydrogenation catalyst comprises sulfur and one or more of molybdenum, tungsten, cobalt, and/or nickel.

A hydrotreated aromatic product stream is taken in line 158 from the hydrotreating unit 157 and can be used as a biofuel or a motor biofuel. In accordance with the present disclosure, the hydrotreating unit 157 may be used to remove the oxygen components. Further, the hydrotreating step may be used to produce a biofuel or a motor biofuel that meets one or both of the smoke point specification, and aromatics limit of the fuel.

The hydrotreated stream in line 158 may be combined with the first alkylated aromatic product stream in line 155 to provide a combined alkylated aromatic product stream in line 159. The combined alkylated aromatic product stream in line 159 can be used as a biofuel or a motor biofuel. In an alternate embodiment, the hydrotreating unit 157 is optionally used and an entirety of the alkylated aromatic product stream in line 153 may bypass the hydrotreating unit 157 and be directly used as a biofuel or a motor biofuel. In an aspect, the combined alkylated aromatic product stream in line 159 may be further processed to provide the biofuel or the motor biofuel.

In an embodiment, the combined alkylated aromatic product stream in line 159 may be fractionated in a fractionation section 160 to provide a diesel stream and a jet fuel stream. The jet fuel stream is taken in line 162 and the diesel stream is taken in line 164 from the fractionation section. The jet fuel stream in line 162 is a green jet fuel and the diesel stream in line 164 is a green diesel in accordance with the present disclosure. In an aspect, the jet fuel stream in line 162 may comprise about 0.1 wt % to about 67 wt % renewable carbon, preferably about 0.1 wt % to about 20 wt % renewable carbon. In another aspect, the diesel stream in line 164 may comprise about 0.1 wt % to about 67 wt % renewable carbon, preferably about 0.1 wt % to about 20 wt % renewable carbon.

EXAMPLE

Propylene was taken as alkylating agent for the alkylation of an aromatic stream in line 142. The aromatic stream predominantly comprised BTX. A combined feed stream in line 144 with a BTX to propylene molar ratio of 2 to 2.2 was used for the study. The BTX stream was alkylated to produce the alkylated aromatic product. The study was performed at various reactor inlet temperatures and recycle mass flow rates. The results are plotted in the graph shown in FIG. 3 showing A9+ aromatics (aromatics with at least nine carbon atoms) concentration at various reactor inlet temperatures and recycle mass flow rates over time. As evident from the graph in FIG. 3, a higher recycle flow rate produced a higher amount of A9+ aromatics which is desirable for jet fuel.

SPECIFIC EMBODIMENTS

While the following is described in conjunction with specific embodiments, it will be understood that this description is intended to illustrate and not limit the scope of the preceding description and the appended claims.

A first embodiment of the present disclosure is a process of producing a fuel stream comprising renewable carbon, comprising producing an alkylating agent stream from a renewable feedstock; and charging an aromatic stream and the alkylating agent stream to an alkylation reactor to alkylate the aromatic stream with the alkylating agent to produce an alkylated aromatic product stream, wherein the alkylated aromatic product stream comprises about 0.1 wt % to about 67 wt % renewable carbon. An embodiment of the present disclosure is one, any or all of prior embodiments in this paragraph up through the first embodiment in this paragraph, wherein the alkylating agent comprises at least one of an alcohol stream and an olefinic stream produced from the renewable feedstock. An embodiment of the present disclosure is one, any or all of prior embodiments in this paragraph up through the first embodiment in this paragraph, wherein the alcohol stream comprises at least one of methanol, ethanol, iso-butanol, and propanol. An embodiment of the present disclosure is one, any or all of prior embodiments in this paragraph up through the first embodiment in this paragraph, wherein the aromatic stream comprises at least one of a reformate stream, a naphtha stream, a kerosene stream, a diesel stream, and a light cycle oil stream. An embodiment of the present disclosure is one, any or all of prior embodiments in this paragraph up through the first embodiment in this paragraph, wherein the alcohol stream is obtained from a lignin stream. An embodiment of the present disclosure is one, any or all of prior embodiments in this paragraph up through the first embodiment in this paragraph further comprising separating a liquid stream from a fermented lignocellulosic biomass; and fractionating the liquid stream to provide an overhead alcohol stream and a bottoms stream comprising lignin. An embodiment of the present disclosure is one, any or all of prior embodiments in this paragraph up through the first embodiment in this paragraph further comprising hydrogenating the alkylated aromatic product stream to produce a fuel stream. An embodiment of the present disclosure is one, any or all of prior embodiments in this paragraph up through the first embodiment in this paragraph further comprising hydrotreating the alkylated aromatic product stream to produce a jet fuel stream and a diesel stream. An embodiment of the present disclosure is one, any or all of prior embodiments in this paragraph up through the first embodiment in this paragraph, wherein the step of alkylating the aromatic stream comprises an alkylation temperature of about 50° C. to about 400° C. and an alkylation pressure of about 1000 kPa to about 10000 kPa. An embodiment of the present disclosure is one, any or all of prior embodiments in this paragraph up through the first embodiment in this paragraph, wherein the step of hydrogenating the alkylated aromatic product stream comprises contacting the alkylated aromatic product stream and a hydrogen stream with a catalyst at a temperature of about 50° C. to about 400° C. and a pressure of about 980 kPa (g) to about 9810 kPa (g). An embodiment of the present disclosure is one, any or all of prior embodiments in this paragraph up through the first embodiment in this paragraph, wherein the alkylating agent is the olefinic stream. An embodiment of the present disclosure is one, any or all of prior embodiments in this paragraph up through the first embodiment in this paragraph, wherein the alkylating agent is the alcohol stream. An embodiment of the present disclosure is one, any or all of prior embodiments in this paragraph up through the first embodiment in this paragraph further comprising dehydrating a bio-derived alcohol stream to produce the olefinic stream.

A second embodiment of the present disclosure is a process of producing a fuel stream comprising renewable carbon, comprising producing an olefinic stream comprising C2 to C5 hydrocarbons or an alcohol stream comprising C2 to C5 hydrocarbons from a renewable feedstock; and charging an aromatic stream produced from a fossil fuel and an alkylating agent comprising the olefinic stream or the alcohol stream to an alkylation reactor to alkylate the aromatic stream with the alkylating agent to produce an alkylated aromatic product stream, wherein the alkylated aromatic product stream comprises about 0.1 wt % to about 67 wt % renewable carbon. An embodiment of the present disclosure is one, any or all of prior embodiments in this paragraph up through the second embodiment in this paragraph, wherein the alcohol stream comprises at least one of methanol, ethanol, iso-butanol, and propanol. An embodiment of the present disclosure is one, any or all of prior embodiments in this paragraph up through the second embodiment in this paragraph, wherein the aromatic stream comprises at least one of a reformate stream, a naphtha stream, a kerosene stream, a diesel stream, and a light cycle oil stream. An embodiment of the present disclosure is one, any or all of prior embodiments in this paragraph up through the second embodiment in this paragraph further comprising separating a liquid stream from a fermented lignocellulosic biomass; and fractionating the liquid stream to provide an overhead stream comprising the alcohol stream and a bottoms stream comprising lignin. An embodiment of the present disclosure is one, any or all of prior embodiments in this paragraph up through the second embodiment in this paragraph further comprising dehydrating a bio-derived alcohol stream to produce the olefinic stream.

A third embodiment of the present disclosure is a process of producing a fuel stream comprising renewable carbon, comprising producing an olefinic stream or an alcohol stream from a renewable feedstock; charging an aromatic stream and an alkylating agent comprising the olefinic stream or the alcohol stream to an alkylation reactor to alkylate the aromatic stream with the alkylating agent to produce an alkylated aromatic product stream, wherein the alkylated aromatic product stream comprises about 0.1 wt % to about 20 wt % renewable carbon; and hydrotreating the alkylated aromatic product stream to produce a fuel stream. An embodiment of the present disclosure is one, any or all of prior embodiments in this paragraph up through the third embodiment in this paragraph, wherein the aromatic stream comprises at least one of a reformate stream, a naphtha stream, a kerosene stream, a diesel stream, and a light cycle oil stream. An embodiment of the present disclosure is one, any or all of prior embodiments in this paragraph up through the third embodiment in this paragraph, wherein the alcohol stream comprises at least one of methanol, ethanol, iso-butanol, and propanol.

Without further elaboration, it is believed that using the preceding description that one skilled in the art can utilize the present disclosure to its fullest extent and easily ascertain the essential characteristics of this disclosure, without departing from the spirit and scope thereof, to make various changes and modifications of the disclosure and to adapt it to various usages and conditions. The preceding preferred specific embodiments are, therefore, to be construed as merely illustrative, and not limiting the remainder of the disclosure in any way whatsoever, and that it is intended to cover various modifications and equivalent arrangements included within the scope of the appended claims.

In the foregoing, all temperatures are set forth in degrees Celsius and, all parts and percentages are by weight, unless otherwise indicated.