Catalytic conversion of lactic acid into propylene glycol over various metals supported on silica

Abstract

Catalytic hydrogenation of lactic acid to propylene glycol was performed over various metals (Ag, Co, Cu, Ni, Pt, and Ru) supported on silica prepared by an incipient wetness impregnation method. The loading amount of each metal was 5 wt%. Crystallinity of the synthesized catalysts was investigated by X-ray diffraction (XRD), and the BET method was utilized to examine the surface area. Pore volume and pore size of catalysts were determined using BJH analysis of the N 2 adsorption isotherm. Particle sizes of various metals were determined from transmission electron microscopy (TEM) images. The catalytic activity was found to be strongly dependent on the supported metal. Among catalysts tested, Ru/SiO 2 showed the highest propylene glycol yield. The yield of propylene glycol increased with pressure, and the highest yield was achieved at 130°C.

Hydrogenation of Lactic Acid to 1,2‐Propanediol over Ru‐Based Catalysts

“…This is in line with earlier studies demonstrating that the formation of 1,2-PDO is generally favored at ah igher pressure, [15a] at least in part because of the strong pressure dependency of H 2 solubility in water. [19] The increase of the LA feed concentration five-fold to 0.5 m while keeping the LA/Ru ratio similar to that of the other tests did not affect substantially the reactiono utcome.Asimilar 1,2-PDO yield of 68 %a t 84 %L Ac onversion could be obtained after 4h reactiona t 180 8C. An appropriate amount of spent catalyst was weighed and utilized in an ext catalytic test following the standard procedure (20 mg catalyst, 0.1 m LA).…”

“…It was found that the yield of 1,2‐PDO linearly increases with increasing reaction pressure (Figure S4). This is in line with earlier studies demonstrating that the formation of 1,2‐PDO is generally favored at a higher pressure, at least in part because of the strong pressure dependency of H 2 solubility in water . The increase of the LA feed concentration five‐fold to 0.5 m while keeping the LA/Ru ratio similar to that of the other tests did not affect substantially the reaction outcome.…”

“…[18] However, the optimal performance of such catalysts could only be established at aH 2 pressure as high as 140 bar.S ubsequent studies mainly focusedo nr educing the temperature and pressurer equirements for the hydrogenation process andt he most representativeresults are summarized in Ta ble 1. [19][20][21][22][23] The catalytic hydrogenation of lactic acid to 1,2-propanediol with supported Ru catalysts in water was investigated. The influence of catalysts upport (activated carbon, g-Al 2 O 3 ,S iO 2 , TiO 2 ,a nd CeO 2 )a nd promoters (Pd, Au, Mo, Re, Sn) on the catalytic performance was evaluated.C atalytic tests revealed that TiO 2 yields the best Ru catalysts.…”

“…However, the optimal performance of such catalysts could only be established at a H 2 pressure as high as 140 bar. Subsequent studies mainly focused on reducing the temperature and pressure requirements for the hydrogenation process and the most representative results are summarized in Table …”

Biologically synthesized crude calcium lactate as a substrate for propylene glycol production

“…Selectivity to PG reached 90-95% under optimal reaction conditions. Jang et al 10 performed liquidphase catalytic hydrogenation of LA (50 mL, 1 M, 110-170 C, 6-9 MPa) over various metals (Ag, Co, Cu, Ni, Pt and Ru) supported on SiO 2 . Of the catalysts tested, Ru/SiO 2 provided the highest PG yield, which increased with pressure.…”