Current status and perspectives in oxidative, non-oxidative and CO₂-mediated dehydrogenation of propane and isobutane over metal oxide catalysts

Abstract

Conversion of propane or isobutane from natural/shale gas into propene or isobutene, which are indispensable for the synthesis of commodity chemicals, is an important environmentally friendly alternative to oil-based cracking processes.

Uncovering selective and active Ga surface sites in gallia–alumina mixed-oxide propane dehydrogenation catalysts by dynamic nuclear polarization surface enhanced NMR spectroscopy

“…5 In this context, the atomic-scale understanding of active sites in Ga 2 O 3 -based PDH catalysts is essential. [6][7][8] It has been argued that the active sites in gallia catalysts are tetracoordinated (Ga IV ) Lewis acidic Ga 3+ surface sites, 1,9 associated with weak Lewis acidity. 10,11 In b-Ga 2 O 3 , weak Lewis acid sites (LAS, assessed using pyridine as a probe molecule) active in PDH have been attributed to tricoordinated Ga sites (Ga III ) with a neighboring oxygen vacancy (V o , when x ¼ 0 in Scheme 1B).…”

Impact of Heteroatom Speciation on the Activity and Stability of Carbon‐Based Catalysts for Propane Dehydrogenation

“…Furthermore, these processes mainly yield ethylene, resulting in a growing gap between the increasing demand for propylene and its limited supply capacity, which calls for more sustainable and versatile production routes [1a] . Consequently, considerable research efforts are devoted to developing “on purpose” technologies that exclusively yield this olefin [4] . Among various catalytic approaches investigated, [5] the non‐oxidative propane dehydrogenation (PDH) finds commercial implementation in the Catofin™ and Oleflex™ processes over supported chromium oxide (CrO x )‐ and platinum‐tin (Pt−Sn)‐based systems [6] .…”

Reducing the irreducible: Dispersed metal atoms facilitate reduction of irreducible oxides.

“…Recently, the above strategies have been successfully applied in the activation of a typical irreducible oxide, zirconia (ZrO 2 ), for nonoxidative dehydrogenation of hydrocarbons by creating oxygen vacancies on the surface of monoclinic zirconia. 10 From a mechanistic perspective, the introduction of oxygen vacancies leads to the formation of coordinatively unsaturated Zr cations, which are active sites for the dehydrogenation reaction. [10][11][12] Crucially, the catalytic activity of ZrO 2 has been directly correlated with its ability to release oxygen, i.e., zirconia's reducibility.…”

“…10 From a mechanistic perspective, the introduction of oxygen vacancies leads to the formation of coordinatively unsaturated Zr cations, which are active sites for the dehydrogenation reaction. [10][11][12] Crucially, the catalytic activity of ZrO 2 has been directly correlated with its ability to release oxygen, i.e., zirconia's reducibility. 10,13 The reducibility and catalytic activity towards hydrocarbon dehydrogenation have successfully been increased by reducing the ZrO 2 particle size.…”

“…[10][11][12] Crucially, the catalytic activity of ZrO 2 has been directly correlated with its ability to release oxygen, i.e., zirconia's reducibility. 10,13 The reducibility and catalytic activity towards hydrocarbon dehydrogenation have successfully been increased by reducing the ZrO 2 particle size. 11,12 Doping ZrO 2 with Ca 2+ , Mg 2+ , and Li + decreases the activity below that of pristine zirconia, whereas introducing La 3+ , Y 3+ , and Sm 3+ dopants promotes reducibility and activity 14,15 -Cr-promoted ZrO 2 was even found to outperform the commercial CrO x -K/Al 2 O 3 catalyst for propane dehydrogenation.…”