Preparation Of Tungsten Carbide Catalyst Supported On CNTs And The Research Of Catalytic Hydrogenation Performance

Cellulose biomass distribute widely, but the present utilization rate is still low, cellulose resources is rich in our country, by way of cellulose catalysis hydrogenation we can produce a lot materials. Tungsten carbide is an important catalyst, widely used in hydrogenation field, it has similar structure to precious metals. The Carbon nanotubes with high mechanical strength, better hydrogen adsorption performance and moderate specific surface area had been widespread used in lots of field. It takes ammonium metatungstate as tungsten source and carbon black as carbon sources, carbon nanotubes as the carrier. Supported catalysts were prepared by carbon hydrogen reduction (CHR) method. And they were investigated into the performance in cellulose catalysis hydrogenation reaction. The different reaction conditions were comparison test, include different reaction time, reaction temperature, different hydrogen gas pressure, different reaction media, find the best reaction conditions. And acquire a series of characterization results of the corresponding catalyst, they include XRD, TPR, TPD, nitrogen physical adsorption method, so as to explore the preparation of catalysts with catalytic properties and structure of the relationship.The results of the Catalytic hydrogenation reaction study show that, tungsten carbide supported by carbon nanotubes as the catalyst of cellulose hydrogenation reaction, the catalyst best loading capacity is30%, the best catalyst roasting temperature is600℃, best activation reduction temperature700-950℃, hydrogenation reaction time is2hours, the best reaction temperature200℃. To hydrogenation product analysis shows that, the conversion of cellulose up to84%, in the optimum reaction conditions on the product yield can reach45%of sorbitol.The preparation of the best reaction performance WC/CNTs catalyst, it’s effective for crystal W2C (PDF-35-0776), activation temperature in the700-800℃, catalyst surface tungsten carbide in the carrier surface gradually gathered together,850～950℃activation, another kind of tungsten carbide (WC) crystal diffraction peak produced and area to increase gradually. Ammonia program temperature show that is "Tm=470℃, Tm=580℃", they are strong acidic center. The hole of the hole form of catalyst is cracks hole, or tapered hole, their specific surface area between90～110m2/g, belong to the pore structure, aperture focused on2～4nm, by the increase of reduction and roasting temperature, surface area reduce gradually, the catalyst hole volume space greatens.