Influence of the Support of Bimetallic Platinum Tungstate Catalysts on 1,3‐Propanediol Formation from Glycerol

Abstract

Three aluminium oxide materials and a HZSM‐5 zeolite were used as supports of bimetallic Pt‐WOx catalysts to establish structure–activity relationships in the glycerol hydrogenolysis reaction. The surface W density and the intimate contact between Pt and WOx were key parameters. Surface W density controls the formation of polytungstates, the only species able to produce the weak Brønsted acidity that is required to produce 1,3‐propanediol selectively. The comparison between the HZSM‐5 and the Al2O3 supports demonstrated that an increment of the medium Brønsted acidity is detrimental for the selective 1,3‐propanediol formation as it promotes reactions that yield 1‐propanol and propane. An increase of the dispersion of Pt on the Pt/WOx/Al2O3 catalysts led to higher glycerol conversions but also promoted the hydrogenolysis routes that lead to 1,2‐ and 1,3‐propanediol similarly. On the contrary, an increase of the Pt metal content favoured the hydrogenolysis route that leads to 1,3‐propanediol significantly. A more intimate contact between Pt and WOx promoted the hydrogenation of the intermediate carbocation, formed and stabilised on a polytungstate active site, into 1,3‐propanediol.

C−O Hydrogenolysis of Tetrahydrofurfuryl Alcohol to 1,5‐Pentanediol Over Bi‐functional Nickel‐Tungsten Catalysts

“…These results indicate that the acidity can mainly be attributed to Lewis acid sites on the surface of catalysts at tungsten surface densities lower than 1.3. According to the previous studies,, below monolayer coverage (tungsten surface density ≪4–5 W nm −2 ), only Lewis acidity attributed to monotungstate WO x species are present on the surface the catalyst. At higher tungsten surface density (i. e., <4–5 W nm −2 ), polytungstate surface WO x species start to be formed, yielding Brønsted acid sites.…”

Advances in porous and nanoscale catalysts for viable biomass conversion

“…464 The significance of support nature and metal addition in improving catalyst stability and product selectivity in glycerol hydrogenolysis is discussed in recent articles. [465][466][467][468][469]…”

Effective Hydrogenolysis of Glycerol to 1,3‐Propanediol over Metal‐Acid Concerted Pt/WOx/Al2O3 Catalysts

“…Driven by the great potential for practical applications, this reaction has been intensively studied . So far, it has been established that a noble metal in combination with an oxophilic metal oxide, typically like Ir−ReO x, Rh−ReO x and Pt−WO x , is effective for the formation of 1,3‐PDO. In comparison with ReO x , WO x offers the advantage of better leaching‐resistance and lower cost, therefore shows greater potential for practical applications.…”