The Study On In Situ Synthesis Of The Molybdenum-based Catalyst@ N-doped Carbon From Biomass And The Hydrodeoxygenation

As one important part of the lignocellulosic biomass, lignin is widely found in nature and essential to human use. The stable three-dimensional cross-linked network of lignin makes it difficult to convert into resources. Traditional direct combustion of lignin is not only lower utilization, but also easy to exhaust greenhouse gases which causing global warming and forest fire issues. In order to make better use of lignin to produce the required energy, researchers have employed pyrolysis biomass method for preparing bio-oil and bio-oil upgrading to use as the transportation fuel.In addition to the preparation of bio-oil, lignin can also be utilized to produce aromatic hydrocarbons which are the major materials in the petrochemical industry. The rich benzene rings in the structure of lignin provide a novel route to gain the aromatic hydrocarbons. However, the benzene rings are linked by a variety of C-O bonds and C-C bonds, which make it difficult to decompose lignin, the high content of oxygen is also greatly limited to convert lignin to higher added value chemicals. Therefore, development of efficiently economic catalysts for the degradation and the hydrodeoxygenation of lignin is the key to comprehensively utilize lignin.The studies are focused on the sulfide cobalt-molybdenum and sulfide nickel-molybdenum catalysts. These sulfide systems can achieve the hydrodeoxygenation of model compounds, but the use of metal sulfide catalysts is constrained by the problems of the inactivation, products contamination and separation. Compared to the sulfide catalysts, the noble metal catalysts have higher catalytic activity for the hydrodeoxygenation, such as Rh, Ru, Pt, Pd, etc. However, oxygenates are easy to form coke on the catalyst surface which results in the decrease of catalyst life in the hydrodeoxygenation process and the noble catalysts cannot achieve large-scale industrial application due to the high cost. The conventional method to prepare catalysts is very complex with long preparation period. The presence of sintering active ingredient and migrating solutes makes it difficult to apply in the large-scale production in the process of drying, calcination and reduction.The molybdenum-based catalyst with high selectivity was one-step prepared using cellulose with molybdenum and ammonia pyrolyzed under 600℃. This task verified the feasibility of MoOx@NC catalysts applying in the hydrodeoxygenation of lignin-derived phenols. Also, complete conversion of the phenols and high selectivity of aromatic hydrocarbons was achieved simultaneously by optimizing the reaction conditions. Under the optimal conditions,1.0 h-1 WHSV of 20 wt% guaiacol at 450℃ with 1.5 g catalyst in hydrogen atmosphere, aromatic hydrocarbons in the carbon yield of 83.3% was obtained and none of phenol products was detected.