Preparative Aspects of Supported Ni2P Catalysts for Reductive Upgrading of Technical Lignin to Aromatics

Supported Ni2P was evaluated as a hydrodeoxygenation (HDO) catalyst in the reductive upgrading of a soda lignin in supercritical ethanol by a hydrotalcite-derived mixed Cu-Mg-Al oxide (CuMgAlOx) catalyst. Various Ni2P catalysts were prepared by different approaches on silica, γ-alumina and a siliceous amorphous silica-alumina (ASA) supports. Calcined NiO/SiO2 precursors were impregnated with phosphate, phosphite and hypophosphite followed by reduction. With γ-alumina, the desired Ni2P could not be obtained, presumably due to the reaction of the P-source with alumina. NiO on ASA could be converted to Ni2P by addition of phosphite, preferably at a P/Ni ratio of 1. Low P/Ni ratio avoids blockage of the pores by P-oxide species remaining after reduction. By further comparison to a sol–gel prepared NiO/SiO2 and co-impregnated silica, it was established that the most active Ni2P catalyst was obtained by impregnation of NiO/SiO2 with phosphate at P/Ni = 1 and reduction at 620 °C. In combination with CuMgAlOx, more than half of soda lignin can be converted to aromatics monomers with a relatively high degree of deoxygenation and limited degree of ring hydrogenation. The co-catalyst system is more active than the separate catalysts

Lewis-acid catalyzed depolymerization of Protobind lignin in supercritical water and ethanol

The use of metal acetates, metal chlorides and metal triflates as Lewis acid catalysts for the depolymerization of soda lignin under supercritical conditions was investigated. The reactions were carried out at 400°C in water and ethanol. Lignin conversion in supercritical water led to formation of insoluble char and resulted in low yields of monomeric products. When the reaction was performed in supercritical ethanol, char formation was inhibited and higher yields of low molecular-weight organic products were obtained. The ethanol solvent was also converted in two ways. Firstly, the lignin depolymerization products were alkylated by ethanol. Secondly, ethanol was converted into a range of higher hydrocarbons including paraffins and olefins. Possible mechanisms of the lignin and ethanol conversion reactions are discussed

Lewis-acid catalyzed depolymerization of Protobind lignin in supercritical water and ethanol

\u3cp\u3eThe use of metal acetates, metal chlorides and metal triflates as Lewis acid catalysts for the depolymerization of soda lignin under supercritical conditions was investigated. The reactions were carried out at 400°C in water and ethanol. Lignin conversion in supercritical water led to formation of insoluble char and resulted in low yields of monomeric products. When the reaction was performed in supercritical ethanol, char formation was inhibited and higher yields of low molecular-weight organic products were obtained. The ethanol solvent was also converted in two ways. Firstly, the lignin depolymerization products were alkylated by ethanol. Secondly, ethanol was converted into a range of higher hydrocarbons including paraffins and olefins. Possible mechanisms of the lignin and ethanol conversion reactions are discussed.\u3c/p\u3