The discovery of the dual aromatic- and olefin-based catalytic cycles in methanol-to-hydrocarbons (MTH) catalysis on acid zeolites has given a new context for rationalizing structure–function relationships for this complex chemistry. This perspective examines six major chemistries involved in the hydrocarbon pool mechanism for MTH—olefin methylation, olefin cracking, hydrogen transfer, cyclization, aromatic methylation, and aromatic dealkylation—with a focus on what is known about the rate and mechanism of these chemistries. The current mechanistic understanding of MTH limits structure–function relationships to the effect of the zeolite framework on the identity of the hydrocarbon pool and the resulting product selectivity. We emphasize the need for assessing the consequences of zeolite structure in MTH in terms of experimentally measured rates and activation barriers for individual reaction steps and in terms of speciation preferences within the dual olefin- and aromatic-catalytic cycles to alter their r...

Mechanism of the Catalytic Conversion of Methanol to Hydrocarbons

The production of high-demand chemical commodities such as ethylene and propylene (methanol-to-olefins), hydrocarbons (methanol-to-hydrocarbons), gasoline (methanol-to-gasoline) and aromatics (methanol-to-aromatics) from methanol—obtainable from alternative feedstocks, such as carbon dioxide, biomass, waste or natural gas through the intermediate formation of synthesis gas—has been central to research in both academia and industry. Although discovered in the late 1970s, this catalytic technology has only been industrially implemented over the past decade, with a number of large commercial plants already operating in Asia. However, as is the case for other technologies, industrial maturity is not synonymous with full understanding. For this reason, research is still intense and a number of important discoveries have been reported over the last few years. In this review, we summarize the most recent advances in mechanistic understanding—including direct C–C bond formation during the induction period and the promotional effect of zeolite topology and acidity on the alkene cycle—and correlate these insights to practical aspects in terms of catalyst design and engineering. The conversion of methanol — which can be produced from non-fossil resources — to important chemical commodities such as olefins and aromatics allows for the diversification of organic feedstocks beyond petrochemicals. This Review covers recent discoveries about the mechanism of this process and discusses how these link to practical aspects in reaction engineering.

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Recent trends and fundamental insights in the methanol-to-hydrocarbons process

Zeolites are versatile and fascinating materials which are vital for a wide range of industries, due to their unique structural and chemical properties, which are the basis of applications in gas separation, ion exchange and catalysis. Given their economic impact, there is a powerful incentive for smart design of new materials with enhanced functionalities to obtain the best material for a given application. Over the last decades, theoretical modeling has matured to a level that model guided design has become within reach. Major hurdles have been overcome to reach this point and almost all contemporary methods in computational materials chemistry are actively used in the field of modeling zeolite chemistry and applications. Integration of complementary modeling approaches is necessary to obtain reliable predictions and rationalizations from theory. A close synergy between experimentalists and theoreticians has led to a deep understanding of the complexity of the system at hand, but also allowed the identification of shortcomings in current theoretical approaches. Inspired by the importance of zeolite characterization which can now be performed at the single atom and single molecule level from experiment, computational spectroscopy has grown in importance in the last decade. In this review most of the currently available modeling tools are introduced and illustrated on the most challenging problems in zeolite science. Directions for future model developments will be given.

https://biblio.ugent.be/publication/6977178/file/8575390.pdf

Samia Ilias

Papers

Mechanism of the Catalytic Conversion of Methanol to Hydrocarbons

Tuning the selectivity of methanol-to-hydrocarbons conversion on H-ZSM-5 by co-processing olefin or aromatic compounds

A descriptor for the relative propagation of the aromatic- and olefin-based cycles in methanol-to-hydrocarbons conversion on H-ZSM-5

The mechanism of aromatic dealkylation in methanol-to-hydrocarbons conversion on H-ZSM-5: What are the aromatic precursors to light olefins?

Mechanism of the Catalytic Conversion of Methanol to Hydrocarbons