CAJ | 학술논문

采用共沉淀法和原位溶胶-凝胶法制备了TiO2-Al2O3复合载体,其负载的磷化镍催化剂采用等体积浸渍法和H2原位还原法制备.通过N2吸附(BET)、X射线衍射(XRD)、透射电镜(TEM)、程序升温还原(TPR), X射线光电子能谱(XPS)和等离子体发射光谱(ICP-AES)表征技术对催化剂进行了表征,并通过喹啉的加氢脱氮反应评价了催化剂的加氢脱氮性能.结果表明,原位溶胶-凝胶法制成的复合载体基本保留了原有的γ-Al2O3的孔特征,具有较大的比表面积和较宽的孔分布, TiO2主要以表面富集的形式分散在管状的γ-Al2O3表面,其负载的磷化镍催化剂还原后所形成的活性相为Ni2P和Ni12P5；而共沉淀法制成的复合载体比表面积较小,孔径分布更加集中, TiO2趋于在块状的Al2O3表面均匀分散,其负载的磷化镍催化剂具有更好的可还原性,还原后所形成的活性相为Ni2P.不同的载体制备方法和不同的钛铝比对催化剂加氢脱氮性能影响较大,当n(Ti)/n(Al)=1/8时,共沉淀法载体负载的催化剂表现出最佳的加氢脱氮性能,在340°C,3 MPa,氢油体积比500,液时空速3 h-1的反应条件下,喹啉的脱氮率可以达到91.3%.
채용공침정법화원위용효-응효법제비료TiO2-Al2O3복합재체,기부재적린화얼최화제채용등체적침지법화H2원위환원법제비.통과N2흡부(BET)、X사선연사(XRD)、투사전경(TEM)、정서승온환원(TPR), X사선광전자능보(XPS)화등리자체발사광보(ICP-AES)표정기술대최화제진행료표정,병통과규람적가경탈담반응평개료최화제적가경탈담성능.결과표명,원위용효-응효법제성적복합재체기본보류료원유적γ-Al2O3적공특정,구유교대적비표면적화교관적공분포, TiO2주요이표면부집적형식분산재관상적γ-Al2O3표면,기부재적린화얼최화제환원후소형성적활성상위Ni2P화Ni12P5；이공침정법제성적복합재체비표면적교소,공경분포경가집중, TiO2추우재괴상적Al2O3표면균균분산,기부재적린화얼최화제구유경호적가환원성,환원후소형성적활성상위Ni2P.불동적재체제비방법화불동적태려비대최화제가경탈담성능영향교대,당n(Ti)/n(Al)=1/8시,공침정법재체부재적최화제표현출최가적가경탈담성능,재340°C,3 MPa,경유체적비500,액시공속3 h-1적반응조건하,규람적탈담솔가이체도91.3%.
TiO2-Al2O3 composite supports were prepared by in situ sol-gel and co-precipitation methods, and the supported nickel phosphide catalysts were prepared by incipient wetness impregnation and the in situ H2 reduction method. The catalysts were characterized by X-ray diffraction (XRD), N2 adsorption (BET), transmission electron microscopy (TEM), temperature-programmed reduction (TPR), X-ray photoelectron spectroscopy (XPS), and inductive couple plasma atomic emission spectrometry techniques (ICP-AES). The hydrodenitrogenation (HDN) activity of the supported nickel phosphide catalysts were evaluated on a continuous-flow fixed-bed reactor using quinoline as the model molecule. The results showed that the composite support prepared by the in situ sol-gel method basical y retained the original pore properties ofγ-Al2O3 but with a larger surface area and decentralized pore size distribution, and TiO2 was enriched on the tubularγ-Al2O3 surface. The composite support prepared by the co-precipitation method had a smal er surface area and a centralized pore size distribution, and TiO2 was evenly dispersed on the massiveγ-Al2O3 surface. The main active phases after reduction were Ni2P and Ni12P5 for the catalyst supported on sol-gel prepared TiO2-Al2O3, but only Ni2P for the catalyst supported on co-precipitated TiO2-Al2O3. Different TiO2-Al2O3 preparation techniques and different Ti/Al atomic ratios had a great effect on the HDN activity of the catalysts. The catalyst supported on co-precipitated TiO2-Al2O3 exhibited better reducibility and HDN activity than the catalyst supported on in situ sol-gel prepared TiO2-Al2O3. The optimal HDN activity occurred for the catalyst supported on co-precipitated TiO2-Al2O3 with an initial Ti/Al atomic ratio of 1:8. At a reaction temperature of 340 °C, pressure of 3 MPa, hydrogen/oil volume ratio of 500, and liquid hourly space velocity of 3 h-1, the HDN conversion of quinoline was 91.3%.