CAJ | 학술논문

在不同焙烧温度和焙烧气氛下对共浸渍法制备的K_2MoO_4-NiO/SiO_2催化剂进行热处理,并采用X射线衍射、热重-差示扫描量热、氢气程序升温还原、拉曼光谱和电子白旋共振波谱等手段对催化剂进行了表征,同时考察了催化剂催化高硫化氧合成气一步法制甲硫醇的性能.结果表明,由于催化剂中所含柠檬酸氧化放热,空气中焙烧的催化剂发生严重烧结.随着焙烧温度的升高,八面体配位的Mo(O_h)逐渐向四面体配化的Mo(T_d)转变,导致催化剂的还原能力降低,配位不饱和Mo(CO吸附位)减少,因而CO转化率降低.甲硫醇的生成与Mo-S-K相密切相关,而MoS_2晶相表面主要生成烃类.与氮气中焙烧的催化剂相比,空气中焙烧的催化剂表面的MoS_2相较多,而Mo-S-K相较少,因此具有更高的烃类选择性和更低的甲硫醇选择性.
재불동배소온도화배소기분하대공침지법제비적K_2MoO_4-NiO/SiO_2최화제진행열처리,병채용X사선연사、열중-차시소묘량열、경기정서승온환원、랍만광보화전자백선공진파보등수단대최화제진행료표정,동시고찰료최화제최화고류화양합성기일보법제갑류순적성능.결과표명,유우최화제중소함저몽산양화방열,공기중배소적최화제발생엄중소결.수착배소온도적승고,팔면체배위적Mo(O_h)축점향사면체배화적Mo(T_d)전변,도치최화제적환원능력강저,배위불포화Mo(CO흡부위)감소,인이CO전화솔강저.갑류순적생성여Mo-S-K상밀절상관,이MoS_2정상표면주요생성경류.여담기중배소적최화제상비,공기중배소적최화제표면적MoS_2상교다,이Mo-S-K상교소,인차구유경고적경류선택성화경저적갑류순선택성.
K_2MoO_4-NiO/SiO_2 catalyst samples prepared by the co-impregnation method were calcined at different temperatures and atmos-phere. X-ray diffraction, thermal gravimetric-differential scanning calorimetry, hydrogen temperature-programmed reduction, Raman spec-troscopy, and electron spin resonance techniques were used to characterize the catalyst samples. The catalytic performance of the catalyst for one-step synthesis of methanethiol from high H_2S-containing syngas was evaluated. The results showed that the catalyst calcined in air sin-tered seriously because of the heat release from citric acid oxidation. With the increase of calcination temperature, octahedral coordination Mo(O_h) gradually changed into tetrahedral coordination Mo(T_d), which made the reduction of Mo~(6+) more difficult, decreased the number of CO adsorption sites (coordinatively unsaturated sites) of Mo, and at last led to the decrease of CO conversion. Methanethiol synthesis was closely related to the Mo-S-K phase, and hydrocarbon synthesis was related to the MoS2 phase. Compared with the catalyst calcined in N_2, there were more MoS_2 phase and less Mo-S-K phase on the surface of the catalyst calcined in air, resulting in the higher selectivity for hy-drocarbon and lower selectivity for CH_3SH.