Conversion of Synthesis Gas to Light Olefins: Impact of Hydrogenation Activity of Methanol Synthesis Catalyst on the Hybrid Process Selectivity over Cr–Zn and Cu–Zn with SAPO-34

Abstract

Direct conversion of syngas to hydrocarbons occurs over hybrid catalyst mixtures containing methanol synthesis and microporous acid components. In particular, both copper and zinc oxide-based as well as chromium-and zinc-based catalysts are active for methanol synthesis and can be used in the hybrid catalyst process. The choice of methanol synthesis catalyst alters product selectivity and distribution. In particular, reaction products of the Cu−Zn/SAPO-34 system include only saturated hydrocarbons, while the Cr−Zn/SAPO-34 catalyst enables light olefin production directly from syngas. Hydrogenation properties of the methanol synthesis catalyst influence the C 3 /C 2 yield ratios in the hydrocarbon products. We analyze the observed differences of selectivity with respect to olefin hydrogenation activities of the methanol synthesis components and their interaction with SAPO-34 for methanol-to-olefins conversion. A simplified kinetic model for the hybrid system is proposed to describe the observed selectivity patterns.

CO2hydrogenation to methanol and hydrocarbons over bifunctional Zn-doped ZrO2/zeolite catalysts

“…34 Carbon mono-and di-oxide activation was reported to be facilitated by the presence of neighbouring cus-Zr 4+ ion sites and V O . 25,[35][36][37] Thus, V O enhance the Brønsted acidity of Zr-OH groups adjacent to cus-Zr 4+ cations. 38 Between the potential dopants, Zn 2+ has been investigated in the formation of ZnZrO X solid solutions.…”

“…Hence, both Zn and ZrO 2 seem to promote several reactions related to environmental concerns. To date, a major fraction of recent works based on Zn-Zr systems deals with syngas conversion 13,36,37 whereas another fraction is devoted to Zn-Zr systems involved in CO 2 hydrogenation aiming for different products, such as methanol. In the case of Zndoped ZrO 2 studied by Wang et al, 31 CO 2 conversion increases up to 20% at high temperatures (>320°C) while methanol selectivity drops to less than 30%.…”

A Review on the Conversion of Synthetic Gas to LPG over Hybrid Nanostructure Zeolites Catalysts

“…The role of metal or metal oxide in the hybrid catalyst is to facilitate the production of methanol as an intermediate product. [100] Several metal sets have been tested with different weight ratio of the metal to zeolite. Majority of these studies used Pd, ZnÀ Cr, ZnÀ M (M = Al 2 O 3 , ZrO 2 , Cr 2 O 3 ), and sometimes they inject Cr, Al, and Ca as a catalyst promoter.…”

“…The role of metal or metal oxide in the hybrid catalyst is to facilitate the production of methanol as an intermediate product [100] . Several metal sets have been tested with different weight ratio of the metal to zeolite.…”

On the reaction mechanism of MnOx/SAPO-34 bifunctional catalysts for the conversion of syngas to light olefins

“…7,9 It is designed in the literature either by OXZEO or more generally by STO (syngas to olefins). Most of oxides contained Zn: ZnO, 11 ZnCrOx, 8,[12][13][14][15][16][17][18][19] ZnZrOx, 10,20,21 ZnAlOx, [22][23][24] Zrpromoted ZnAlOx, 25 La-doped ZnAlOx, 26 Zn spinels, 27 ZnCeZrOx. [28][29][30][31] Alternatively, MnOx, 32 MnGaOx, 33,34 or ZrInOx, 35 was used.…”