制备条件对非负载Ni-Mo复合氧化物催化剂加氢脱氧性能的影响

Effects of Preparation Conditions on the Properties of Unsupported Ni-Mo Composite Oxide Catalysts for Hydrodeoxygenation

以柠檬酸为络合剂,采用溶胶-凝胶法制备了非负载Ni-Mo复合氧化物催化剂,用N2吸附-脱附、XRD、SEM等手段对催化剂进行了表征。在连续流动固定床反应器上,以乙酸为探针分子考察了不同溶液pH值和溶剂量制备催化剂对催化加氢脱氧性能的影响。结果表明:溶胶-凝胶法制备的催化剂具有较高的比表面积和双介孔结构;主要以复合氧化物NiMoO4的形式存在;改变溶液的pH值和溶剂量,对催化剂的比表面积有一定影响。在初始溶液pH=1、溶剂量855 mL(mol(Ni+Mo))1的条件下制备的催化剂具有较优异的加氢脱氧活性,在0.3 MPa,250℃,液时空速2 h 1的条件下,催化剂催化乙酸加氢脱氧的转化率和脱氧率分别达到99.9%和98.9%。

Unsupported Ni-Mo composite oxide catalysts were successfully prepared by the sol-gel method with citric acid as the complex agent, and the prepared catalysts were characterized by using N2 adsorption-desorption, X-ray diffraction （XRD）, and SEM. In a continuous flow fixed-bed reactor, the effects of pH value and solvent volume used during preparation on the hydrodeoxygenation activity of the prepared catalysts were investigated emphatically by using acetic acid as probe compounds. The results show that the catalysts prepared by sol-gel method could possess higher specific surface area and the double mesoporous structure. The XRD patterns show that the Ni and Mo existing in the catalysts are in the form of composite oxide NiMoO4. During preparation, changing pH value of solution and solvent volume can positively effect the specific surface area of catalysts. The catalysts prepared at the conditions of pH=1 and solvent volume =855 mL.（mol （Ni＋Mo））-1 xhibit the highest hydrodeoxygenation activity. At 0.3 MPa, 250℃, LHSV=2 h^-1, the deoxygenation ratio and conversion ratio of the acetic acid are 99.9% and 98.9%, respectively.