Synthesis of bimetallic catalysts supported on alumina by an aqueous sol-gel process

The thermochemical method called “biomass gasification” is generating emphatic interest for the production of bio-Syngas (CO+H2) since this process presents the advantage of being renewable without emitting CO2. However, in practical applications, there are still some technical problems due to high concentration of tars in the outlet gas, which can condensate and clog the pipes. Previous studies have highlighted the fact that the tar elimination via catalytic reforming seem to be the more practical and economical solution.
Catalysts were synthesized by an aqueous sol-gel process to develop γ-Al2O3 doped with 10 wt.% of nickel and 2 wt.% of a second dopant (Co, Cu, Fe, Mn, Mo). Before their adding in AlOOH sol, metallic dopants were complexed with (OCH3)3-Si-(CH2)3-NH-(CH2)2-NH2 (EDAS) to increase their dispersion by cogelation between EDAS and AlOOH clusters.
All the samples were tested for toluene reforming at 650°C for 300 min. No previous reduction step has been realized. Each 15 min, injection was sent to a GC Compac for analysis.
For samples Al2O3-10Ni-2Mn and Al2O3-10Ni-2Mo, the addition of Mn or Mo allows increasing the toluene conversion up to 100%, whereas all other samples present lower toluene conversion (around 30%). Taking into account the benzene selectivity, it is observed that Mn and Mo are both elements that favor the degradation of aromatic groups. In term of carbon deposit during catalytic test, sample Al2O3-10Ni-2Mn is the most interesting doping since only 0.04 gcarbon gcata-1 is depicted by TG-DSC measurement after catalytic test.