Highly stable phosphine modified VOx/Al2O3 catalyst in propane dehydrogenation

Abstract

The relatively low cost and mild toxicity of vanadium makes it an alternative to commercially applied Pt and Cr based catalysts in propane dehydrogenation (PDH). Conventional VOx/Al2O3 catalyst shows high initial activity, but deactivates fast due to severe coke formation, which requires frequent regeneration by coke combustion and causes massive CO2 emissions. In this context, we report on the phosphine (PH3) surface modification of VOx/Al2O3 catalyst leading to substantial improvement of its stability. The phosphorus considerably modifies the properties of the VOx/Al2O3 catalyst: (i) tunes surface acidity, (ii) separates polymerized vanadium oxide species and (iii) weakens interaction between vanadium species with alumina support. Synergy among all these factors facilitate desorption of produced propylene and inhibit the oligomerization of coke precursors, which contributed to the enhancement of the catalyst stability during propane dehydrogenation.

Propane dehydrogenation over extra-framework In(i) in chabazite zeolites

“…1 PDH technologies, i.e., the Catofin process using CrO x /Al 2 O 3 catalyst, and the Oleflex process using supported Pt-Sn catalyst have drawbacks, such as the high cost and rapid deactivation of Pt and the potential environmental impact caused by Cr. Many other catalysts for PDH have been investigated including Ga-, [2][3][4][5][6][7][8][9][10] Zn-, 11,12 Co-, [13][14][15] Fe-, [16][17][18] V-, [19][20][21][22] Zr-based materials, [23][24][25] and nanocarbon catalysts. 26,27 Metal cations (Ga + , Zn 2+ , Co 2+ , etc.)…”

A Novel Method of 3D Printing High‐Loaded Oxide/H‐ZSM‐5 Catalyst Monoliths for Carbon Dioxide Reduction in Tandem with Propane Dehydrogenation

“…To address these issues, other soft oxidants, such as nitrous oxide and carbon dioxide, have been considered as co‐feeds in propane dehydrogenation reaction. [ 5,6 ] The utilization of CO 2 as a soft oxidant does not form an explosive reactive mixture (unlike oxygen), prevents over oxidation of propylene and propane, and alters the pathway by providing an oxygen atom that combines with the hydrogen atoms from the propane CH bond scission to give water. This makes the reaction feasible at a lower operating temperature, due to its favorable thermodynamics compared to direct dehydrogenation of propane.…”

“…), have been studied for their activity in the CO 2 ‐ODHP reaction; as these particular oxides provide the necessary active sites to reduce CO 2 into CO, while the support provides the acid surface sites necessary to dehydrogenate propane into propylene. [ 6,10,11 ] Yet, there are ex situ catalyst characterization data with little detailed information on the CO 2 and propane activation mechanisms that exist. These bifunctional catalysts are commonly synthesized and evaluated as powders and cannot be directly implemented into industrial reaction processes because high flow rates will lead to scattering and material loss.…”

Fabrication of Isolated VOx Sites on Alumina for Highly Active and Stable Non-Oxidative Dehydrogenation

“…Alternatively, MgO addition is also applied to lower the deactivation rate of VO x /Al 2 O 3 for non-oxidative dehydrogenation of propane, but the result is still unsatisfactory . Moreover, phosphine (PH 3 ) surface modification of the VO x /Al 2 O 3 catalyst leads to substantial improvement of its stability for non-oxidative dehydrogenation of propane . However, the propylene selectivity is lower than 90%.…”

“…21 Moreover, phosphine (PH 3 ) surface modification of the VO x /Al 2 O 3 catalyst leads to substantial improvement of its stability for non-oxidative dehydrogenation of propane. 22 However, the propylene selectivity is lower than 90%. In view of these, the development of a highly active and stable vanadium-based catalyst remains a huge challenge.…”