ClassID:

32962

B01J29/18 - CPC Classification

Classification description:

Catalysts comprising molecular sieves having base-exchange properties, e.g. crystalline zeolites; Crystalline aluminosilicate zeolites; Isomorphous compounds thereof of the mordenite type

Sub-classes:
Recent Application in this class:
#1
20260091378
2026-04-02

RED MUD AND MORDENITE ZEOLITE CATALYST FOR SIMULTANEOUS DEHALOGENATION AND CONVERSION OF PLASTIC DERIVED OIL TO FUELS AND CHEMICALS

#2
20260001065
2026-01-01

METAL-CONTAINING MOR-TYPE ZEOLITES FOR CAPTURE OF CARBON DIOXIDE FROM LOW-CO2 CONTENT SOURCES AND METHODS OF USING THE SAME

#3
20250162889
2025-05-22

MORDENITE ZEOLITE HAVING EXCELLENT PARTICLE UNIFORMITY AND METHOD FOR PREPARING THE SAME

#4
20250122161
2025-04-17

PROCESS FOR PREPARING A OXACYLOHEXANE OR OXACYLOPENTANE DERIVATIVE

#5
20250011264
2025-01-09

CYCLIC COMPOUND AND METHOD FOR PRODUCING CYCLIC COMPOUND

#6
20240409485
2024-12-12

PROCESS FOR PREPARING CRESOL FROM DITOLYLETHER

#7
20230249167
2023-08-10

Catalyst compositions and their use in aromatic alkylation processes

#8
20230235142
2023-07-27

Methods for processing polyolefins

#9
20230234038
2023-07-27

METAL-CONTAINING MOR-TYPE ZEOLITES FOR CAPTURE OF CARBON DIOXIDE FROM LOW-CO2 CONTENT SOURCES AND METHODS OF USING THE SAME

#10
20230173472
2023-06-08

PROCESS AND CATALYST FOR THE PREPARATION OF ETHYLENE

#11
20230001393
2023-01-05

CATALYST FOR PYROLYSIS OF 1,2-DICHLOROETHANE (DCE) TO PREPARE VINYL CHLORIDE (VC) AND PREPARATION METHOD, USE, AND REGENERATION METHOD THEREOF

#12
20220185755
2022-06-16

Process for dehydrating methanol to dimethyl ether

#13
20220144748
2022-05-12

Method for producing methyl acetate by means of carbonylation of dimethyl ether

#14
20220126278
2022-04-28

Catalysts and processes for converting aromatics

#15
20220098136
2022-03-31

Process for dehydrating methanol to dimethyl ether

#16
20220097032
2022-03-31

Molecular sieve catalyst, preparation method therefor, and application thereof

#17
20220088572
2022-03-24

Nano-Structured Composite Materials for Chemical Air Pollutant and Odor Removal from Air

#18
20220048013
2022-02-17

Catalytic composition and structures made thereof

#19
20220008901
2022-01-13

Post-synthetic downsizing zeolite-type crystals and/or agglomerates thereof to nanosized particles

#20
20210205795
2021-07-08

UZM-54 and transalkylation process using same

#21
20210187486
2021-06-24

Process for making modified small-crystal mordenite, transalkylation process using same, and modified small-crystal mordenite

#22
20210179437
2021-06-17

Mordenite Zeolite Having Excellent Particle Uniformity and Method for Preparing Same

#23
20210163390
2021-06-03

Process for dehydrating methanol to dimethyl ether

#24
20210163389
2021-06-03

Process for dehydrating methanol to dimethyl ether product

#25
20210139337
2021-05-13

Process for the synthesis, with multiple seeding, of zeolite crystals having a controlled particle size

#26
20210114963
2021-04-22

Method for preparing acrylic acid and methyl acrylate

#27
20210040016
2021-02-11

Process for co-production of mixed xylenes and high octane C aromatics

#28
20200385322
2020-12-10

Transalkylation Process and Catalyst Composition Used Therein

#29
20200376471
2020-12-03

Catalyst compositions and their use in aromatic alkylation processes

#30
20200368733
2020-11-26

Process for making modified small-crystal mordenite, transalkylation process using same, and modified small-crystal mordenite

#31
20200354303
2020-11-12

Carbonylation process for the production of methyl acetate

#32
20200346992
2020-11-05

Organic base modified composite catalyst and method for producing ethylene by hydrogenation of carbon monoxide

#33
20200283354
2020-09-10

Process of making olefins or alkylate by reaction of methanol and/or DME or by reaction of methanol and/or DME and butane

#34
20200246775
2020-08-06

Supported zeolite films and methods for preparing

#35
20200239401
2020-07-30

Method for directly producing methyl acetate and/or acetic acid from syngas

#36
20200230583
2020-07-23

Zeolite with rare earth element-substituted framework and method for producing same, and NOx adsorber, selective catalytic reduction catalyst and automobile exhaust gas catalyst comprising same

#37
20200190005
2020-06-18

Process for dehydrating methanol to dimethyl ether product

#38
20200179913
2020-06-11

Catalyst compositions and their use in aromatic alkylation processes

#39
20200123315
2020-04-23

Ortho alkoxy bisphenol monomers

#40
20200115248
2020-04-16

Functional structural body and method for making functional structural body

#41
20200109057
2020-04-09

Method for synthesizing mordenite MOR molecular sieve, and product and use thereof

#42
20200078777
2020-03-12

Catalyst composition

#43
20200062686
2020-02-27

Method for preparing low-grade unsaturated fatty acid ester

#44
20200031755
2020-01-30

Process for carbonylating dimethyl ether

#45
20190314794
2019-10-17

Treatment of aromatic alkylation catalysts

#46
20190299491
2019-10-03

Catalytic process of simultaneous pyrolysis of mixed plastics and dechlorination of the pyrolysis oil

#47
20190284057
2019-09-19

Methods of producing composite zeolite catalysts for heavy reformate conversion into xylenes

#48
20190262814
2019-08-29

Method for synthesizing a FER/MOR composite molecular sieve

#49
20190262811
2019-08-29

Catalyst for synthesizing aromatic hydrocarbons and preparation method therefor

#50
20190218158
2019-07-18

Process of making olefins or alkylate by reaction of methanol and/or DME or by reaction of methanol and/or DME and butane

#51
20190134614
2019-05-09

POROUS CERAMIC BODY TO REDUCE EMISSIONS

#52
20190134613
2019-05-09

Isomerization Catalyst, Method for Producing Linear Olefin and Method for Producing Compound

#53
20190039054
2019-02-07

Mesoporous zeolites and methods for the synthesis thereof

#54
20190016647
2019-01-17

Process for producing ethylbenzene

#55
20190002767
2019-01-03

Process to prepare propylene

#56
20190002369
2019-01-03

Process to prepare propylene

#57
20180371616
2018-12-27

METHOD OF FORMING AN ALUMINOSILICATE-ZEOLITE LAYER ON AN ALUMINIUM-CONTAINING METALLIC SUBSTRATE AND USE OF THE SUBSTRATE OBTAINED THEREBY

#58
20180369795
2018-12-27

Catalyst composition, its preparation and process using such composition

#59
20180369794
2018-12-27

Carbonylation process using a pretreated zeolite catalyst

#60
20180326408
2018-11-15

Dual catalyst system for propylene production

#61
20180311654
2018-11-01

Zeolite-based compound having high crystallinity, method for producing the same, and method for producing methyl acetate using the same

#62
20180304245
2018-10-25

Carbonylation catalyst and process

#63
20180280948
2018-10-04

Selective catalytic reduction catalyst

#64
20180280947
2018-10-04

Selective catalytic reduction catalyst

#65
20180273455
2018-09-27

Method for directly preparing glycol dimethyl ether and co-producing ethylene glycol from ethylene glycol monomethyl ether

#66
20180272323
2018-09-27

Catalytic composition and structures made thereof

#67
20180265369
2018-09-20

Process for preparing a molecular sieve

#68
20180251413
2018-09-06

Transalkylation processes and catalyst compositions used therein

#69
20180244599
2018-08-30

Method for preparing acetic acid by carbonylation of methanol

#70
20180194635
2018-07-12

Method for the preparation of synthetic crystalline zeolite materials with enhanced pore volume

#71
20180179123
2018-06-28

Process for producing cumene and/or sec-butylbenzene using a mixed olefins stream as alkylation agent

#72
20180169634
2018-06-21

Porous ceramic body to reduce emissions

#73
20180158558
2018-06-07

Adsorbent for adsorbing iodine compounds and/or antimony, method for preparing said adsorbent, and method and apparatus for treating radioactive waste liquid by using said absorbent

#74
20180155256
2018-06-07

Dual catalyst system for propylene production

#75
20180134647
2018-05-17

Method to produce acrylic acid with acetaldehyde as the main by-product

#76
20180126365
2018-05-10

FCC catalyst compositions containing boron oxide

#77
20180021762
2018-01-25

Heat generating catalyst for hydrocarbons cracking

#78
20170369390
2017-12-28

Catalytic process for producing olefins

#79
20170368540
2017-12-28

ISOPARAFFIN-OLEFIN ALKYLATION

#80
20170334818
2017-11-23

Method for preparing double-sealed-end glycol ether

#81
20170326534
2017-11-16

Heat generating catalyst for hydrocarbons cracking

#82
20170320807
2017-11-09

Method for preparing methyl formate and coproducing dimethyl ether

#83
20170305752
2017-10-26

Crystalline molecular sieves and synthesis thereof

#84
20170225959
2017-08-10

Solidothermal synthesis of zeolitic materials and zeolites obtained therefrom

#85
20170158798
2017-06-08

Process for the production of di- and polyamines of the diphenylmethane series

#86
20170144140
2017-05-25

Cracking catalyst composition for cracking of heavy hydrocarbon feed stocks and process for preparing the same

#87
20170144139
2017-05-25

Composition and process for preparation of cracking catalyst suitable for enhancing yields of light olefins

#88
20170113981
2017-04-27

Process of making olefins or alkylate by reaction of methanol and/or DME or by reaction of methanol and/or DME and butane

#89
20170072389
2017-03-16

Catalyst For A Naphtha Reforming Process

#90
20170072387
2017-03-16

Process for preparing a catalyst

#91
20170056864
2017-03-02

Composition and a process for preparation of attrition resistant cracking catalyst suitable for enhancing light olefins

#92
20170051212
2017-02-23

Naphtha reforming process

#93
20170022066
2017-01-26

Crystalline molecular sieves and synthesis thereof

#94
20170001927
2017-01-05

Dual catalyst system for propylene production

#95
20170001926
2017-01-05

Systems and methods for producing propylene

#96
20170001180
2017-01-05

Catalyst composition for isomerization of paraffins

#97
20160375430
2016-12-29

Catalyst for direct production of isoparaffins-rich synthetic oil and a method for preparing the catalyst

#98
20160289141
2016-10-06

METHOD AND APPARATUS FOR CARRYING OUT ENDOTHERMIC REACTIONS

#99
20160257571
2016-09-08

Catalyst for producing higher silane and process for producing higher silane

#100
20160221832
2016-08-04

Process for preparing a molecular sieve

#101
20160052857
2016-02-25

Carbonylation process

#102
20160016881
2016-01-21

Process for the carbonylation of dimethyl ether

#103
20160016155
2016-01-21

Carbonylation catalyst and process

#104
20160009629
2016-01-14

Carbonylation process

#105
20160008761
2016-01-14

SCR catalytic converter having improved NOx conversion

#106
20160002271
2016-01-07

Production method for alkoxysilanes

#107
20150360211
2015-12-17

Process for treating zeolite catalysts

#108
20150352541
2015-12-10

Catalyst system having meso and macro hierarchical pore structure

#109
20150322352
2015-11-12

Method for producing monocyclic aromatic hydrocarbons

#110
20150299106
2015-10-22

Pentenenitrile isomerization

#111
20150298983
2015-10-22

Organotemplate-free solid-state synthetic method for zeolite molecular sieves

#112
20150298108
2015-10-22

Method for preparing methyl acetate

#113
20150231614
2015-08-20

METHOD FOR PRE-TREATING A CATALYST COMPOSITION

#114
20150182953
2015-07-02

Introducing mesoporosity into zeolite materials with a modified acid pre-treatment step

#115
20150158784
2015-06-11

Process to make olefins from organics

#116
20150152021
2015-06-04

Process to make olefins and aromatics from organics

#117
20150152020
2015-06-04

Process to make olefins from oxygenates

#118
20150126357
2015-05-07

Nano-structured composite absorber for air detoxing and deodoring

#119
20150099912
2015-04-09

Process to make olefins from oxygenates

#120
20150094511
2015-04-02

Additives for maximizing light olefins in fluid catalytic cracking and process units

#121
20140364634
2014-12-11

Process for carrying out a reaction involving a liquid reaction mixture

#122
20140322781
2014-10-30

Catalytic conversion of alcohols to hydrocarbons with low benzene content

#123
20140316098
2014-10-23

Process for producing phenol

#124
20140256538
2014-09-11

Zeolite core/silica zeolite shell composite, preparing method of the same, and catalyst including the same

#125
20140256010
2014-09-11

Catalytic conversion of alcohols to hydrocarbons with low benzene content

#126
20140228606
2014-08-14

Conversion of plastics to olefin and aromatic products with product recycle

#127
20140213432
2014-07-31

Methods for enhancing the mesoporosity of zeolite-containing materials

#128
20140163275
2014-06-12

Producing method of monocyclic aromatic hydrocarbons and monocyclic aromatic hydrocarbon production plant

#129
20140079611
2014-03-20

B-type iron silicate composition and method for reducing nitrogen oxides

#130
20140058157
2014-02-27

Process for increasing a mole ratio of methyl to phenyl

#131
20140046108
2014-02-13

Method for controlling 2-phenyl isomer content of linear alkylbenzene and catalyst used in the method

#132
20140038810
2014-02-06

Method for controlling 2-phenyl isomer content of linear alkylbenzene and catalyst used in the method

#133
20140024866
2014-01-23

Catalysts for thermo-catalytic conversion of biomass, and methods of making and using

#134
20130316895
2013-11-28

Fibrous substrate-based hydroprocessing catalysts and associated methods

#135
20130299389
2013-11-14

Mesostructured zeolitic materials, and methods of making and using the same

#136
20130267748
2013-10-10

Catalyst regeneration process

#137
20130253247
2013-09-26

Catalysts, processes for preparing the catalysts, and processes for transalkylating aromatic hydrocarbon compounds

#138
20130225397
2013-08-29

Binderless molecular sieve catalyst and a preparation method thereof

#139
20130202509
2013-08-08

Diesel oxidation catalyst

#140
20130190166
2013-07-25

NOx reduction catalyst for exhaust gas and method for producing same

#141
20130183231
2013-07-18

Introduction of mesoporosity into zeolite materials with sequential acid, surfactant, and base treatment

#142
20130157840
2013-06-20

Molecular sieve composition from pre-formed extrudates and process of use

#143
20130123096
2013-05-16

Organotemplate-free synthetic process for the production of a zeolitic material

#144
20130121890
2013-05-16

PHOTOCATALYST-CONTAINING FILTER MATERIAL, AND PHOTOCATALYST FILTER INCLUDING THE FILTER MATERIAL

#145
20130045860
2013-02-21

Organotemplate-free synthetic process for the production of a zeolitic material

#146
20130041198
2013-02-14

Highly active decomposition catalyst for low carbon hydrocarbon production from sulfur containing fuel

#147
20130030232
2013-01-31

CATALYST FOR PRODUCTION OF MONOCYCLIC AROMATIC HYDROCARBONS AND METHOD OF PRODUCING MONOCYCLIC AROMATIC HYDROCARBONS

#148
20130023710
2013-01-24

FCC catalyst additive and a method for its preparation

#149
20130015102
2013-01-17

Catalyst for production of hydrocarbons and method of producing hydrocarbons

#150
20130005564
2013-01-03

SYNTHESIS OF CRYSTALLINE LONG-RANGED ORDERED MATERIALS FROM PREFORMED AMORPHOUS SOLIDS

#151
20120298554
2012-11-29

Fibrous substrate-based hydroprocessing catalysts and associated methods

#152
20120296135
2012-11-22

Nitrogen containing catalyst for coupling reactions

#153
20120277330
2012-11-01

Process for producing transportation fuels from syngas

#154
20120258852
2012-10-11

Mesoporous framework-modified zeolites

#155
20120144733
2012-06-14

Condensation of glycols to produce biofuels

#156
20120116139
2012-05-10

Multiple zeolite catalyst

#157
20120101298
2012-04-26

Carbonylation process

#158
20120078005
2012-03-29

Carbonylation process

#159
20120065446
2012-03-15

Catalysts, processes for preparing the catalysts, and processes for transalkylating aromatic hydrocarbon compounds

#160
20120065444
2012-03-15

Method for controlling 2-phenyl isomer content of linear alkylbenzene and catalyst used in the method

#161
20120053360
2012-03-01

Carbonylation process

#162
20120024776
2012-02-02

Mesostructured zeolitic materials, and methods of making and using the same

#163
20110306785
2011-12-15

Selective dealumination of MOR type zeolites

#164
20110240519
2011-10-06

Process and apparatus for alkylating and hydrogenating a light cycle oil

#165
20110218356
2011-09-08

Carbonylation process catalysed by mordenite supported on inorganic oxides

#166
20110207981
2011-08-25

Alkylation process using catalysts with low olefin skeletal isomerization activity

#167
20110201864
2011-08-18

Dual-zeolite catalyst for production of ethylbenzene

#168
20110196113
2011-08-11

Process to make olefins and aromatics from organics

#169
20110178259
2011-07-21

Process to make olefins from organics

#170
20110166303
2011-07-07

Process to make olefins from oxygenates

#171
20110152479
2011-06-23

Process to make olefins from oxygenates

#172
20110144402
2011-06-16

Alkylation process using catalysts with low olefin skeletal isomerization activity

#173
20110118107
2011-05-19

Methods for enhancing the mesoporosity of zeolite-containing materials

#174
20110098513
2011-04-28

Process for making diethyl ether from acetic acid

#175
20110077441
2011-03-31

Production of aromatics from methane

#176
20100322847
2010-12-23

Organotemplate-free synthetic process for the production of a zeolitic material

#177
20100298598
2010-11-25

Method of preparing a molecular sieve composition

#178
20100288675
2010-11-18

Catalyst for converting acid-containing inferior crude oil and process for making and using the same

#179
20100285949
2010-11-11

Process for rejuvenating a catalyst composition

#180
20100264066
2010-10-21

Aluminum sulfate bound catalysts

#181
20100256431
2010-10-07

Cracking of Olefins on Phosphorus Modified Molecular Sieves

#182
20100145127
2010-06-10

Catalytic composition for producing olefins by catalytic cracking

#183
20100145123
2010-06-10

Olefin upgrading process

#184
20100144514
2010-06-10

Process for Making Catalyst for Olefin Upgrading

#185
20100135864
2010-06-03

Photocatalytic material and photocatalytic member and purification device using the photocatalytic material

#186
20100092383
2010-04-15

Mesostructured zeolitic materials and methods of making and using the same

#187
20100081565
2010-04-01

Aluminum Phosphate Binder for Extruded Catalyst

#188
20100075831
2010-03-25

Multiple molecular sieve catalyst for sour service dewaxing

#189
20100029467
2010-02-04

Multiple zeolite catalyst

#190
20100009842
2010-01-14

Enhancement of alkylation catalysts for improved supercritical fluid regeneration

#191
20090326177
2009-12-31

Mesostructured zeolitic materials and methods of making and using the same

#192
20090325785
2009-12-31

Selective catalyst for aromatics conversion

#193
20090299115
2009-12-03

Dual zeolite catalyst comprising a group VIII metal and a group IIIA metal, and its use in isomerization of aromatic C8 compounds

#194
20090299111
2009-12-03

(ALKYLPHENYL) ALKYLCYCLOHEXANE AND METHOD FOR PRODUCING (ALKYLPHENYL) ALKYLCYCLOHEXANE OR ALKYLBIPHENYL

#195
20090270245
2009-10-29

CATALYTIC MATERIALS AND METHOD FOR THE PREPARATION THEREOF

#196
20090264693
2009-10-22

Process for the catalytic conversion of hydrocarbons

#197
20090163354
2009-06-25

PURIFICATION STRUCTURE INCORPORATING AN ELECTROCHEMICAL CATALYSIS SYSTEM

#198
20090093661
2009-04-09

Catalyst comprising an EUO zeolite, a 10 MR zeolite and a 12 MR zeolite, and its use in isomerizing aromatic C8 compounds

#199
20090090657
2009-04-09

Mesostructured zeolitic materials and methods of making and using the same

#200
20090084090
2009-04-02

Catalyst and Catalyst Structure for Reduction of Nitrogen Oxides, and Method for Catalytic Reduction of Nitrogen Oxides

#201
20090068079
2009-03-12

Compositions and processes for reducing NOemissions during fluid catalytic cracking

#202
20090048093
2009-02-19

CARBON-BASED MATERIAL COMBUSTION CATALYST, MANUFACTURING METHOD OF THE SAME, CATALYST CARRIER, AND MANUFACTURING METHOD OF THE SAME

#203
20090038990
2009-02-12

CATALYST USED FOR CONVERTING COAL TAR TO DIESEL OIL, ITS PREPARATION METHOD AND USE THEREOF

#204
20090005600
2009-01-01

Shaped body comprising a microporous material and at least one silicon-containing binding agent method for production and use thereof as catalyst in particular in a method for continuous synthesis of methylamines

#205
20090005236
2009-01-01

Mesostructured zeolitic materials and methods of making and using the same

#206
20080318764
2008-12-25

Catalytic naphtha cracking catalyst and process

#207
20080139860
2008-06-12

Method for the treatment of a small-and/or medium-pore zeolite and use thereof in the oligomerisation of light olefins

#208
20070244347
2007-10-18

Mesostructured zeolitic materials and methods of making and using the same

#209
20070238605
2007-10-11

Catalysts for the Simultaneous Removal of Carbon Monoxide and Hydrocarbons from Oxygen-Rich Exhaust Gases and Processes for the Manufacture Thereof

#210
20070227351
2007-10-04

Mesostructured zeolitic materials, and methods of making and using the same

#211
20070203017
2007-08-30

Process for preparation of liquefied petroleum gas selective cracking catalyst

#212
20070142688
2007-06-21

Shaped catalysts for transalkylation of aromatics for enhanced xylenes production

#213
20070117709
2007-05-24

Catalyst for dimethyl ether synthesis and its preparation methods

#214
20060264318
2006-11-23

Zeolite composite, method for making and catalytic application thereof

#215
20060242904
2006-11-02

Catalyst for producing liquefied petroleum gas, process for producing the same, and process for producing liquefied petroleum gas with the catalyst

#216
20060182681
2006-08-17

Catalytic materials and method for the preparation thereof

#217
20060142626
2006-06-29

Alkylated aromatic compositions, zeolite catalyst compositions and processes for making the same

#218
20060142625
2006-06-29

Alkylated aromatic compositions, zeolite catalyst compositions and processes for making the same

#219
20060128555
2006-06-15

Zeolite composite, method for making and catalytic application thereof

#220
20060100089
2006-05-11

Enhancement of alkylation catalysts for improved supercritical fluid regeneration

#221
20060051277
2006-03-09

Method and device for reducing the NO and NO of gases

#222
20060036119
2006-02-16

Alkylated aromatic compositions, zeolite catalyst compositions and process for making the same

#223
20060009669
2006-01-12

Mordenite zeolite alkylation catalyst

#224
20050239634
2005-10-27

Mesostructured zeolitic materials, and methods of making and using the same

#225
20050234279
2005-10-20

Catalyst comprising a 10MR zeolite and a 12MR zeolite, and its use in transalkylation of alkylaromatic hydrocarbons

#226
20050232839
2005-10-20

Compositions and processes for reducing NOx emissions during fluid catalytic cracking

#227
20050203323
2005-09-15

Mordenite zeolite alkylation catalysts

#228
20050202954
2005-09-15

Alkylated aromatic compositions, zeolite catalyst compositions and processes for making the same

#229
20050194289
2005-09-08

Zeolites and molecular sieves and the use thereof

#230
20050171385
2005-08-04

Catalysed acylation of alkylated benzene derivatives

#231
20050152823
2005-07-14

Combustion catalysts and processes for removing organic compounds

#232
20050130832
2005-06-16

Catalytic naphtha cracking catalyst and process

#233
20050075526
2005-04-07

Catalytic naphtha cracking catalyst and process

#234
20050049438
2005-03-03

Process utilizing zeolites as catalysts/catalyst precursors

#235
20050038307
2005-02-17

Zeolite catalysts for transalkylation of diisopropylbenzol

#236
20050026771
2005-02-03

Shaped catalysts for transalkylation of aromatics for enhanced xylenes production

#237
18183294
2024-08-20

Integrated processes and systems for producing para-xylenes

#238
17354797
2022-06-07

Zeolite catalyst and method for preparation of aromatic tricyclic pyrans