Production of propylene glycol (propane-1,2-diol) in vapor phase over Cu–Ni/γ-Al2O3 catalyst in a down flow tubular reactor: effect of catalyst calcination temperature and kinetic study

Continuous Flow Upgrading of Selected C2–C6Platform Chemicals Derived from Biomass

“…However, methanol was again utilized as the solvent and a high H 2 /glycerol molar ratio (100) was utilized (Table , entry 11). Good results as well were reported over a Ni–Cu bimetallic catalyst supported on alumina. , 98% glycerol conversion and 89% selectivity for 1,2-propanediol were maintained for 42 h of continuous operation at 220 °C and 7.5 bar of H 2 counterpressure (Table , entry 9). The most economically-viable continuous process was probably reported by Hwang and coworkers, which involved a highly concentrated aqueous glycerol feed (80 wt %), a relatively high WHSV (0.5 h –1 ), and a small hydrogen/glycerol ratio (8) .…”

“…171,265,267,433,434,436,437,[439][440][441]448 The most relevant catalysts and optimized conditions for continuous flow hydrogenolysis of glycerol into 1,2-PDO are summarized in Table 17. Various supported monometallic 265,440,441,446,450−453 and bimetallic 158,267,442,443,454,455 catalysts based on copper were studied, as well as supported Ni, 444 Ni−Ag, 447 and Ru 448,456,457 catalysts. The best results were obtained with copper catalysts (Table 17, entries 1−13), which is interesting from economical and environmental viewpoints.…”

“…Over acidic sites, glycerol is first dehydrated either into acetol ( 29 ) or into 3-hydroxypropanal ( 53 ), depending on the nature of the acid site (Lewis/Brønsted, see Section ). Then carbonyl reduction in the presence of molecular hydrogen, catalyzed by the metallic sites of the catalyst, transforms 29 and 53 into either 1,2- or 1,3-PDO, respectively. ,− ,− Some authors also suggested that glycerol undergoes a double dehydration into acrolein ( 52 ) that is then further rehydrated into 3-hydroxypropanal for the 1,3-PDO formation mechanism. , Over basic sites, glycerol is dehydrogenated into glyceraldehyde ( 51 ) as the first step. Then dehydration is triggered, and following a keto-enol tautomerization, pyruvaldehyde ( 18 ) is finally reduced over metallic sites by molecular hydrogen into 1,2-PDO. , In general, 1,3-PDO formation is favored at lower temperature compared to 1,2-PDO formation. , In most reports, the efficiency of the catalysts developed for the hydrogenolysis of glycerol into propane­diols was related to the presence of widely-dis­persed and small-sized metallic particles, result­ing in a high avail­ability of hydro­gen­ation active sites. ,,,,,,,,− ,− The presence of acid or basic sites of appro­priate strength and con­cen­tration was also key to the successful out­come of the reaction since they provided active sites for de­hydration reactions. ,,,,,,,− , …”

“…However, methanol was again utilized as the solvent and a high H 2 /glycerol molar ratio (100) was utilized (Table17, entry 11). Good results as well were reported over a Ni−Cu bimetallic catalyst supported on alumina 442,443. 98% glycerol conversion and 89% selectivity for 1,2-propanediol were maintained for 42 h of continuous operation at 220 °C and 7.5 bar of H 2 counterpressure (Table17, entry 9).…”

Recent Advances in Glycerol Catalytic Valorization: A Review

“…As active metals in glycerol hydrogenolysis catalysts, the activity of Ir-, Pd-, Ru-, and Pt-based noble metals has been widely reported [108,139,140]. However, recent advances have focused on catalyst cost reduction, and efforts have especially focused on a supported Cu-based catalyst that has reported nearly complete glycerol conversions and 1,2-PDO yields higher than 80% [122,129,[141][142][143][144]. In this sense, the work of Gatti et al [145], with Ni supported over γ-Al 2 O 3 and a phosphorous-impregnated carbon composite in a consecutive treatment of crude glycerol, reached total conversion and yields of 87% 1,2-PDO in the first reaction with Ni/γ-Al 2 O 3 and, after the second hydrogenolysis reaction, obtained 1-PrOH with a 79% yield.…”