Hydrocarbons from Methanol

Chang, Clarence D.

doi:10.1080/01614948308078874

Cited by 738 publications

(224 citation statements)

References 90 publications

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“…The chemical shifts were referenced to 85% H 3 PO 4 at 0 ppm. 1 H MAS NMR spectra were recorded using a 4 mm MAS probe. The pulse width was 2.2 μs for a π/4 pulse, and 32 scans were accumulated with a 4 s recycle delay.…”

Section: Methodsmentioning

confidence: 99%

“…1,2 The methanolto-olefin (MTO) process has proven to be the most successful nonpetrochemical route for the production of light olefins, such as ethylene and propylene, from the abundant resources of natural gas or coal. 3 Aluminosilicate zeolite ZSM-5 4−6 and silicoaluminophosphate molecular sieve SAPO-34 7−9 are excellent catalysts for the MTO reactions.…”

Section: Introductionmentioning

confidence: 99%

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Nanosize-Enhanced Lifetime of SAPO-34 Catalysts in Methanol-to-Olefin Reactions

et al. 2013

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In this work, we systematically investigated the size effect of silicoaluminophosphate molecular sieve catalysts SAPO-34 on the catalytic performance of methanol-to-olefin (MTO) reactions. Four highly crystalline SAPO-34 molecular sieves with different crystallite sizes were synthesized under hydrothermal conditions carried out in conventional or microwave ovens with the same starting gel composition using TEAOH as the structure-directing agent. The as-prepared SAPO-34s have similar composition, and their average crystal size can be controlled between 20 nm and 8 μm.Textural properties and chemical environments of framework atoms as well as acid concentration were characterized by N 2 adsorption and NMR measurements. The MTO reactions were carried out over these four SAPO-34 catalysts to study their catalytic performances dependent on the crystal size. The occurrence of catalyst deactivation varied considerably with the crystal size of SAPO-34s. Significantly, the nanosized catalysts, especially the sheetlike SAPO-34 catalyst with 20 nm thickness, exhibited the longest catalyst lifetime and lowest coking rate in MTO reactions. On the basis of the measurement of coke formation and the determination of retained coke species, a scheme is proposed to elucidate the reduction in coke deposition and consequently the remarkably enhanced lifetime on the nanosized SAPO-34 catalysts in methanol conversion.

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Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Nanosize-Enhanced Lifetime of SAPO-34 Catalysts in Methanol-to-Olefin Reactions

et al. 2013

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“…However, in comparison with methanol dehydration to DME, such reactions are known to take place at relatively higher temperatures and substantially higher contact times [29]. Having this in mind, similar sets of experiments were repeated with different catalyst systems to investigate any possible effect from by-products or catalyst interactions.…”

Section: Effect Of the Dehydration Catalystmentioning

confidence: 99%

Direct dimethyl ether synthesis from synthesis gas: The influence of methanol dehydration on methanol synthesis reaction

et al. 2016

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Direct dimethyl ether (DME) synthesis from synthesis gas is studied with regard to potential effects of methanol dehydration on methanol formation and copperbased catalyst performance. For this, the influence of the operating conditions (space velocity, temperature, pressure, time-on-stream and syngas composition) on activity, selectivity and stability of the catalyst was studied and compared for methanol synthesis and direct DME synthesis. The advantage of the direct over the two-step DME synthesis is apparent at conditions where syngas conversion to methanol is thermodynamically limited. However, under the applied operating conditions, results suggest that combining methanol synthesis and dehydration has a negative effect on the methanol formation kinetics. The origin of the observed phenomena is investigated by varying dehydration catalyst and by introducing dehydration products (DME and water) into the methanol synthesis feed. Choice of the solid acid catalyst does not seem to affect methanol formation, and DME is also found to be practically inert over the methanol synthesis catalysts. Water injection, on the other hand, led to a significant decrease in the methanol synthesis rate. Thus, formation of an additional amount of water through methanol dehydration might be an explanation for the lower methanol formation rate in the direct DME synthesis.

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“…This high initial activity is concluded to be associated with the transient period, during which ammonia is taken up by the mordenite catalyst. In this period, methanol reacts on free Brønsted acid sites via surface methoxy species (1). As the time on stream proceeded, all acid sites became covered with (methyl)ammonium ions, and, thus, the rate of DME formation decreased drastically.…”

Section: Formation Of Dimethyl Ethermentioning

confidence: 99%

“…During the past decades, zeolites have been successfully applied as catalysts for intermediate and fine chemical synthesis (1)(2)(3). While the relatively small pores of the zeolites limit their utilization to the synthesis of small molecules, the well-defined and narrow pore size distribution can be used to induce shape selectivity (4)(5)(6)(7)(8) by (i) allowing only certain reactants to reach the active sites (reactant selectivity) (9), (ii) imposing diffusional constraints on bulkier reaction products (product selectivity) (10,11), or (iii) excluding the formation of certain products due to spatial constraints (restricted transition state selectivity) (12).…”

Section: Introductionmentioning

confidence: 99%

Selectivity Enhancement in Methylamine Synthesis via Postsynthesis Modification of Brønsted Acidic Mordenite

Grundling

Eder‐Mirth

Lercher

1996

Journal of Catalysis

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Methylamine synthesis from methanol and ammonia over parent and modified Brønsted acidic mordenites is studied by in situ infrared spectroscopy and kinetic analysis to elucidate the role of elementary steps for activity and selectivity. In situ infrared spectroscopy reveals that all methylammonium ions are formed in the micropores of these catalysts. The formation of the chemisorbed methylamines, however, is not rate determining. Transient response experiments indicate that the desorption of these methylamines aided by adsorbing ammonia and/or the scavenging of methyl groups with ammonia constitutes the rate determining step. For a given catalyst, the selectivity strongly depends on the methanol conversion and the ammonia to methanol ratio of the feed. Upon modification of mordenite with tetraethoxysilane, the selectivity to the lower methylated amines is strongly enhanced. The transport limitations of the bulkier products, formed in high concentration in the pores, are concluded to cause the enhanced selectivity toward mono-and dimethylamine over the modified catalyst. Since a decrease in activity compared to the parent sample was not observed, it seems that the methyl-scavenging mechanism plays an important role over these catalysts.

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Hydrocarbons from Methanol

Cited by 738 publications

References 90 publications

Nanosize-Enhanced Lifetime of SAPO-34 Catalysts in Methanol-to-Olefin Reactions

Nanosize-Enhanced Lifetime of SAPO-34 Catalysts in Methanol-to-Olefin Reactions

Direct dimethyl ether synthesis from synthesis gas: The influence of methanol dehydration on methanol synthesis reaction

Selectivity Enhancement in Methylamine Synthesis via Postsynthesis Modification of Brønsted Acidic Mordenite

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