Mapping the Methanol‐to‐Gasoline Process Over Zeolite Beta

Abstract

Decarbonizing the transportation sector is among the biggest challenges in the fight against climate change. CO2‐neutral fuels, such as those obtained from renewable methanol, have the potential to account for a large share of the solution, since these could be directly compatible with existing power trains. Although discovered in 1977, the zeolite‐catalyzed methanol‐to‐gasoline (MTG) process has hardly reached industrial maturity, among other reasons, because maximizing the production of gasoline range hydrocarbons from methanol has proved complicated. In this work, we apply multimodal operando UV/Vis diffuse reflectance spectroscopy coupled with an online mass spectrometer and “mobility‐dependent” solid‐state NMR spectroscopy to better understand the reaction mechanism over zeolites H‐Beta and Zn‐Beta. Significantly, the influential co‐catalytic role of oxymethylene species is linked to gasoline formation, which impacts the MTG process more than carbonylated species.

Efficient One‐pot Zeolite Synthesis Protocol from the Metastable *BEA to MTW Topology and Its Impact on the Methanol‐to‐Hydrocarbons Process

“…This observation reveals the descriptor role of HMB + species during the reaction, which was previously reported to be an essential hydrocarbon pool (HCP) species during the MTH process over the zeolite *BEA. [61,68,76] The similar nature of 12MR pore in both MTW and *BEA endows IZC-7, 9, and 13 the analogous reaction patterns. The non-identical spectral pattern of IZC-16 material implies its different framework structures (possibly due to the existence of mixed-phase), which led to other preferential HCP species forming during the catalysis.…”

“…Not only the acidity features, the zeolite topology (especially mixed phases in IZC-16), pore system, and particle size would collectively impact the catalytic performance in the current study (vide supra). The zeolite *BEA (3D) should be worth mentioning for being prone to make gasoline-ranged hydrocarbons during the MTH process, [46,60,61] while zeolite MTW (1D) has been shown to exhibit a preference for C 4 + products. [45,62] The hydrocarbon selectivity analysis in Figure 3 revealed that the C 4 -C 7 (gasoline-ranged) paraffins accounted for 40-60 % of all catalysts before the deactivation.…”

“…Besides that, the excellent C 4 -C 7 selectivity of four zeolite materials could be related to the higher amount of dimethoxy methane (as observed by solid-state NMR-based investigation), as the descriptor role of dimethoxy methane toward the production of gasoline-ranged hydrocarbon product was recently established by us. [61] The "descriptor" or "spectator" role played by all these identified reactive intermediates is significant as different frameworks could stabilize these species preferentially during the IZC process. [10] The hydrogen-deficient compound formaldehyde could participate MTH reaction cycle through a series of reactions, i. e., hydrogen-transfer reaction, aldol reaction, Prins reaction, and others that influence catalysis differently.…”