Hydrogenolysis Of Sorbitol Research Articles

Hydrogenolysis of sorbitol over Ni and Pt loaded on NaY

Abstract The hydrogenolysis of sorbitol (15% aqueous solution) was carried out at 60 bar pressure at 220 °C in a stirred batch reactor using Ni–NaY (2, 4, 6 wt.% Ni) with and without added Pt(1 wt.%). 1,2-Propanediol was the major product over Ni–NaY and glycerol was the main product over Pt(1 wt.%)–NaY. The addition of 1 wt.% Pt to the Ni-catalysts had only a marginal effect on conversion and selectivity of the catalysts. Addition of Ca(OH)2 as the promoter to both Ni and Pt catalysts increased the conversion significantly without any significant effect on selectivity.

Carbon nanofibers supported Ru catalyst for sorbitol hydrogenolysis to glycols: Effect of calcination

Carbon nanofiber (CNFs) supported Ru catalysts for sorbitol hydrogenolysis to ethylene glycol and propylene glycol were prepared by incipient wetness impregnation, calcination and reduction. The effect of calcination on catalyst properties was investigated using thermal gravimetry analysis, temperature-programmed reduction, X-ray diffraction, X-ray photoelectron spectroscopy, transmission electron microscopy and N2 physisorption. The results indicated that calcination introduced a great amount of surface oxygen-containing groups (SOCGs) onto CNF surface and induced the phase transformation of Ru species, but slightly changed the texture of Ru/CNFs. The catalytic performance in sorbitol hydrogenolysis showed that Ru/CNFs catalyst calcined at 240 °C presented the highest glycol selectivities and reasonable glycol yields. It was believed that the inhibition and confinement effect of SOCGs around Ru particles as well as the high dispersion of Ru particles was the key factor for the catalytic activity.

Carbon nanofiber/graphite-felt composite supported Ru catalysts for hydrogenolysis of sorbitol

Carbon nanofiber/graphite-felt (CNF/GF) composite was used to support ruthenium (3.0 wt.%) for sorbitol hydrogenolysis. The CNF/GF composite was synthesized by in situ growing a CNF layer on graphite felt using Ni as catalyst and ethane as carbon source, and Ru was deposited by incipient wetness impregnation. The composite and catalyst were characterized by scanning electron microscopy, N 2 physisorption, X-ray diffraction, and high resolution transmission electron microscopy. The monolithic Ru catalyst was then used as stirring blades in an autoclave, in which sorbitol hydrogenolysis was carried out. The results showed that, compared with the powder Ru/CNF catalyst, the structured Ru catalyst had a lower activity but a much higher total selectivity, from 57.0% to 79.1%, to ethylene glycol, propylene glycol and glycerol.

Hydrogenolysis of sorbitol to glycols over carbon nanofiber supported ruthenium catalyst

Sorbitol hydrogenolysis was carried out over a carbon nanofiber supported ruthenium catalyst prepared by incipient wetness impregnation. The carbon nanofiber supported ruthenium catalyst was shown to have an attracting behavior when compared with a commercial activated carbon supported ruthenium catalyst, especially in terms of selectivity to glycols. The preferable hydrogen partial pressure for sorbitol hydrogenolysis was ca. 8.0 MPa, lower than that usually reported in previous works. Slightly soluble calcium hydroxide, which was used as a basic promoter, remarkably increased the selectivity to glycols, as compared with the soluble sodium hydroxide. The variation of product selectivity with catalyst amount indicated that glycerol was the initial C3 polyol product while propylene glycol was derived from glycerol. The parametric investigation was further focused on the intrinsic features of sorbitol hydrogenolysis.

Catalytic hydrogenolysis of sorbitol

Sorbitol hydrogenolysis on a Ru catalyst shows a dependence on pH and temperature. In a basic medium, the main reaction is a reverse aldolization which gives, among others, a mixture of products containing two or three carbon atoms independently of the temperature. In a neutral medium, the lowering of the temperature leads to an increase in selectivity of hydrogenolysis in the middle of the carbon chain of sorbitol, giving mainly glycerol and 1,2-propanediol. The competition between the hydrogenolysis of C−C and C−O bonds is also discussed.