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

Atomically dispersed noble metal catalysts often exhibit high catalytic performances, but the metal loading density must be kept low (usually below 0.5%) to avoid the formation of metal nanoparticles through sintering. We report a photochemical strategy to fabricate a stable atomically dispersed palladium-titanium oxide catalyst (Pd1/TiO2) on ethylene glycolate (EG)-stabilized ultrathin TiO2 nanosheets containing Pd up to 1.5%. The Pd1/TiO2 catalyst exhibited high catalytic activity in hydrogenation of C=C bonds, exceeding that of surface Pd atoms on commercial Pd catalysts by a factor of 9. No decay in the activity was observed for 20 cycles. More important, the Pd1/TiO2-EG system could activate H2 in a heterolytic pathway, leading to a catalytic enhancement in hydrogenation of aldehydes by a factor of more than 55.

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Photochemical route for synthesizing atomically dispersed palladium catalysts

Methanol-to-hydrocarbons: catalytic materials and their behavior

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

Reference LPI-ARTICLE-1999-017View record in Web of Science Record created on 2006-02-21, modified on 2017-05-12

/pdf/metal-oxide-surfaces-and-their-interactions-with-aqueous-22jt31pax0.pdf

Metal Oxide Surfaces and Their Interactions with Aqueous Solutions and Microbial Organisms.

The process of converting methanol to hydrocarbons on the aluminosilicate zeolite HZSM-5 was originally developed as a route from natural gas to synthetic gasoline. Using other microporous catalysts that are selective for light olefins, methanol-to-olefin (MTO) catalysis may soon become central to the conversion of natural gas to polyolefins. The mechanism of methanol conversion proved to be an intellectually challenging problem; 25 years of fundamental study produced at least 20 distinct mechanisms, but most did not account for either the primary products or a kinetic induction period. Recent experimental and theoretical work has firmly established that methanol and dimethyl ether react on cyclic organic species contained in the cages or channels of the inorganic host. These organic reaction centers act as scaffolds for the assembly of light olefins so as to avoid the high high-energy intermediates required by all “direct” mechanisms. The rate of formation of the initial reaction centers, and hence the d...

The mechanism of methanol to hydrocarbon catalysis.

Methylbenzenes Are the Organic Reaction Centers for Methanol-to-Olefin Catalysis on HSAPO-34

Physical Organic Chemistry of Solid Acids: Lessons from in Situ NMR and Theoretical Chemistry

The oligomerization reactions of propene on zeolite catalyst HY have been studied in detail by in situ variable-temperature /sup 13/C solid-state NMR with cross polarization (CP) and magic-angle spinning (MAS). Propene is shown to be highly mobile in the zeolite at temperatures far below the onset of chemical reactivity. Alkoxy species formed between protonated alkenes and zeolite framework oxygens are found to be important long-lived intermediates in the reactions. Simple secondary or tertiary carbocations either do not exist as free ions in the zeolite at low temperature or are so transient that they are not detected by NMR, even at temperatures as low as 163 K. There is, however, evidence for long-lived alkyl-substituted cyclopentenyl carbocations, which are formed as free ions in the zeolite at room temperature. These carbocations do not form until all of the propene is consumed and hence do not play a significant role in the oligomerization reactions. A detailed mechanism is proposed to account for all of the experimental observations. Novel experimental techniques are introduced which will be applicable to the study of many highly reactive catalyst/adsorbate systems.

Reactions of propene on zeolite HY catalyst studied by in situ variable-temperature solid-state nuclear magnetic resonance spectroscopy

In situ 13C NMR measurements on samples prepared using a pulse-quench catalytic reactor show that the 1,3-dimethylcyclopentenyl carbenium ion (1) is an intermediate in the synthesis of toluene from ethylene on zeolite catalyst HZSM-5. Cation 1 forms in less than 0.5 s when ethylene is pulsed onto the catalyst bed at 623 K, and its presence obviates the kinetic induction period for conversion of a subsequent pulse of dimethyl ether, or methanol, into olefins (MTO chemistry). The kinetic induction period returns when the interval between pulses is many times the half-life of 1 in the catalyst bed. Density functional theory calculations (B3LYP/ 6-311G**) on a cluster model of the zeolite confirm that 1 is stable in the zeolite as a free cation and suggest why the alternative framework alkoxy is not observed. A π complex of the neutral cyclic diene is only 2.2 kcal/mol higher in energy than that of the ion pair. Theoretical (GIAO-MP2/tzp) 13C isotropic shifts of isolated 1 are in good agreement with the exper...

James F. Haw

Papers

The mechanism of methanol to hydrocarbon catalysis.

Methylbenzenes Are the Organic Reaction Centers for Methanol-to-Olefin Catalysis on HSAPO-34

Physical Organic Chemistry of Solid Acids: Lessons from in Situ NMR and Theoretical Chemistry

Reactions of propene on zeolite HY catalyst studied by in situ variable-temperature solid-state nuclear magnetic resonance spectroscopy

Roles for Cyclopentenyl Cations in the Synthesis of Hydrocarbons from Methanol on Zeolite Catalyst HZSM-5