Lignocellulosic biomass pyrolysis mechanism: A state-of-the-art review

Liquid hydrocarbon fuels play an essential part in the global energy chain, owing to their high energy density and easy transportability. Olefins play a similar role in the production of consumer goods. In a post-oil society, fuel and olefin production will rely on alternative carbon sources, such as biomass, coal, natural gas, and CO(2). The methanol-to-hydrocarbons (MTH) process is a key step in such routes, and can be tuned into production of gasoline-rich (methanol to gasoline; MTG) or olefin-rich (methanol to olefins; MTO) product mixtures by proper choice of catalyst and reaction conditions. This Review presents several commercial MTH projects that have recently been realized, and also fundamental research into the synthesis of microporous materials for the targeted variation of selectivity and lifetime of the catalysts.

Conversion of Methanol to Hydrocarbons: How Zeolite Cavity and Pore Size Controls Product Selectivity

The methanol-to-olefins (MTO) reaction is an interesting and important reaction for both fundamental research and industrial application. The Dalian Institute of Chemical Physics (DICP) has developed a MTO technology that led to the successful construction and operation of the world’s first coal to olefin plant in 2010. This historical perspective gives a brief summary on the key issues for the process development, including studies on the reaction mechanism, molecular sieve synthesis and crystallization mechanism, catalyst and its manufacturing scale-up, reactor selection and reactor scale-up, process demonstration, and commercialization. Further challenges on the fundamental research and the directions for future catalyst improvement are also suggested.

http://pubs.acs.org/doi/pdf/10.1021/acscatal.5b00007

Methanol to Olefins (MTO): From Fundamentals to Commercialization

Conversion of methanol to hydrocarbons over zeolite H-ZSM-5 : On the origin of the olefinic species

Catalytic transformations of syngas (a mixture of H2 and CO), which is one of the most important C1-chemistry platforms, and CO2, a greenhouse gas released from human industrial activities but also a candidate of abundant carbon feedstock, into chemicals and fuels have attracted much attention in recent years. Fischer-Tropsch (FT) synthesis is a classic route of syngas chemistry, but the product selectivity of FT synthesis is limited by the Anderson-Schulz-Flory (ASF) distribution. The hydrogenation of CO2 into C2+ hydrocarbons involving C-C bond formation encounters similar selectivity limitation. The present article focuses on recent advances in breaking the selectivity limitation by using a reaction coupling strategy for hydrogenation of both CO and CO2 into C2+ hydrocarbons, which include key building-block chemicals, such as lower (C2-C4) olefins and aromatics, and liquid fuels, such as gasoline (C5-C11 hydrocarbons), jet fuel (C8-C16 hydrocarbons) and diesel fuel (C10-C20 hydrocarbons). The design and development of novel bifunctional or multifunctional catalysts, which are composed of metal, metal carbide or metal oxide nanoparticles and zeolites, for hydrogenation of CO and CO2 to C2+ hydrocarbons beyond FT synthesis will be reviewed. The key factors in controlling catalytic performances, such as the catalyst component, the acidity and mesoporosity of the zeolite and the proximity between the metal/metal carbide/metal oxide and zeolite, will be analysed to provide insights for designing efficient bifunctional or multifunctional catalysts. The reaction mechanism, in particular the activation of CO and CO2, the reaction pathway and the reaction intermediate, will be discussed to provide a deep understanding of the chemistry of the new C1 chemistry routes beyond FT synthesis.

New horizon in C1 chemistry: breaking the selectivity limitation in transformation of syngas and hydrogenation of CO2 into hydrocarbon chemicals and fuels

The widely debated reaction mechanism for the conversion of methanol to hydrocarbons over acidic zeolite H-ZSM-5 has been investigated using isotopic labeling. The mechanistic findings for H-ZSM-5 are clearly different from those previously described at a detailed level for H-β and H-SAPO-34 catalysts. On the basis of the current set of data, we can state that, for H-ZSM-5, ethene appears to be formed exclusively from the xylenes and trimethylbenzenes. Moreover, propene and higher alkenes are to a significant extent formed from alkene methylations and interconversions. This implies that ethene formation is mechanistically separated from the formation of higher alkenes, an insight of utmost importance for understanding and possibly controlling the ethene/propene selectivity in methanol-to-alkenes catalysis.

Conversion of methanol into hydrocarbons over zeolite H-ZSM-5: ethene formation is mechanistically separated from the formation of higher alkenes.

Phosphorous modified ZSM-5: Deactivation and product distribution for MTO

Process for converting oxygenate compounds to hydrocarbons comprising the steps: (a) introducing a feed stream of synthesis gas to a synthesis section for the production of easily convertible oxygenates, (b) passing the effluent stream from said synthesis section containing easily convertible oxygenates to a gasoline synthesis section, (c) passing the effluent of said gasoline synthesis section to a separator and withdrawing from said separator hydrocarbons boiling in the gasoline boiling range, (d) admixing a recycle stream from the separator containing unconverted synthesis gas volatile hydrocarbons with the feed stream of synthesis gas of step (a), (e) introducing a feed containing difficulty convertible oxygenates to the synthesis section of step (a).

Process for converting difficultly convertible oxygenates to gasoline

HZSM-5 is a unique catalyst for the conversion of methanol, dimethyl ether and other oxygenates into gasoline During this process, catalyst deactivation by coking requires frequent regeneration and the improvement of catalyst life time is one of the challenges in catalyst development In this study, a series of mesoporous samples consisting of a ZSM-5 core and a silicalite shell have been synthesized and characterized by XRD, N2-sorption, IR spectroscopy and electron microscopy techniques Additionally, desilicated conventional and mesoporous ZSM-5-type samples were investigated All samples were tested in the MTG reaction, and the results showed that both the shell-coated and the desilicated zeolites are significantly more resistant to coke formation These results are ascribed to the effect of the removal of structural defects rather than to an improvement of the diffusion properties due to the formation of mesopores

Jesper Nerlov

Papers

Conversion of methanol to hydrocarbons over zeolite H-ZSM-5 : On the origin of the olefinic species

Conversion of methanol into hydrocarbons over zeolite H-ZSM-5: ethene formation is mechanistically separated from the formation of higher alkenes.

Phosphorous modified ZSM-5: Deactivation and product distribution for MTO

Process for converting difficultly convertible oxygenates to gasoline

Synthesis and characterization of mesoporous ZSM-5 core-shell particles for improved catalytic properties