Catalytic hydrogenolysis of biodiesel derived glycerol to 1,2-propanediol over Cu–MgO catalysts

Abstract

Selective hydrogenolysis of glycerol to 1,2-propanediol over Cu-MgO catalysts is reported. A series of Cu-MgO catalysts with varying Cu content were prepared by a co-precipitation method. The physico-chemical properties of the catalysts were derived from BET surface area, X-ray diffraction, temperature programmed reduction of hydrogen, temperature programmed desorption of carbon dioxide, X-ray photoelectron spectroscopy, transmission electron microscopy and dissociative N 2 O adsorption techniques. The activity results showed that Cu content on MgO has a significant role in glycerol conversion as well as formation of 1,2-propanediol. Well dispersed Cu species and accessible basic sites of MgO are the essential requirements for high glycerol hydrogenolysis activity. 20 wt% of Cu content on MgO is identified as an optimum Cu content. The catalyst is equally active even with crude glycerol and glycerol containing alkali salts as impurity. Different reaction parameters were evaluated and optimized reaction conditions were established.

Liquid phase conversion of Glycerol to Propanediol over highly active Copper/Magnesia catalysts

“…The surface area decreased sharply with increasing Cu loading from 70.3 m 2 /g (for 5Cu/MgO) to 24.5 m 2 /g (for 25Cu/MgO) probably due to the formation of CuO clusters on the MgO support which might be blocking the pores of MgO. 15 Barret-Joyner-Halenda (BJH) method is applied to desorption branch of isotherms to calculate the pore volume. The pore volume of all catalysts is observed to be in the range of 0.13-0.03 (cm 3 /g).…”

“…Copper chromite, a conventional hydrogenation catalyst, showed good performance in the glycerol hydrogenolysis to 1,2-PDO (65% glycerol conversion with 90% 1,2-PDO selectivity) 12 Chaminand et al 13 hydrogen pressure but the conversion was very low (17%) at longer reaction time of 90 h. Huang et al 14 reported 29% glycerol conversion and 99% 1,2-PDO selectivity over Cu/SiO2 catalyst at 180 • C and 9 MPa hydrogen pressure. Balaraju et al 15 achieved 49.3% conversion over Cu-MgO catalyst with 92% of selectivity for 1,2-PDO after 8 h at moderate reaction conditions (4 MPa 200 • C). Guo et al 16 described Cu/Al 2 O 3 catalyst showed 96.8% selectivity to propanediols with a glycerol conversion of 49.6% at 220 • C, 1.5 MPa initial H 2 pressure after 10 h. More recently, mixed metal oxides such as Cu/Zn-Mg-Al, 17 Cu/ZnO/ZnAl 2 O 4 18 and Cu-Zn-Cr-Zr 19 were reported as highly active and achieved 80-100% glycerol conversions.…”

“…However, the selectivity towards 1,2-PDO is poor due to the propagation of C-C bond cleavage, which leads to the degradation products. Cu-based catalysts [12][13][14][15][16][17][18][19] have been widely studied for glycerol hydrogenolysis to propanediols, mainly because of their high selectivity towards C-O bond hydro-dehydrogenation and poor activity towards C-C bond cleavage. Copper chromite, a conventional hydrogenation catalyst, showed good performance in the glycerol hydrogenolysis to 1,2-PDO (65% glycerol conversion with 90% 1,2-PDO selectivity) 12 Chaminand et al 13 hydrogen pressure but the conversion was very low (17%) at longer reaction time of 90 h. Huang et al 14 reported 29% glycerol conversion and 99% 1,2-PDO selectivity over Cu/SiO2 catalyst at 180 • C and 9 MPa hydrogen pressure.…”

Influence of the carrier and composition of active phase on physicochemical and catalytic properties of CuAg/oxide catalysts for selective hydrogenolysis of glycerol

“…This results in a large quantity of glycerol available for conversion. All of this has resulted in an oversupply of glycerol and a drastic drop in its market price [2]. As a consequence, glycerol is considered one of the most important compounds in conversion of biomass-derived feedstock to value-added chemicals [3,4].…”

“…Another disadvantage of noble-metal catalysts is their high cost. On the contrary, transition-metal catalysts are cheap and offer much greater selectivity for 1,2-propanediol (even close to 100 %), but the glycerol conversion is limited and requires severe reaction conditions [2]. Most transition-metal catalysts contain copper, as it is known to be an effective catalyst in glycerol hydrogenolysis to 1,2-propanediol by selective cleavage of C-O bond instead of C-C bond [12].…”