有机氯硅烷高沸物催化裂解材料研究进展

有机硅材料具有防潮、耐腐蚀、耐高低温、无毒无味以及生理惰性等优异的性能,已被广泛应用于各个领域.有机硅单体的生产过程会产生约7％的副产物,以成分复杂及工业价值低的有机氯硅烷高沸物为主,因其易燃、有刺激性气味和具有强的腐蚀性,对环境及人体健康有重大危害.随着有机硅单体产能日益增加,有机氯硅烷高沸物的有效利用成为一个亟待解决的难题.高沸物的再利用主要是通过制备有机硅下游产品和裂解制备有机硅单体来实现,而后者需要在催化剂存在的条件下将高沸物中含有的Si-Si键和Si-C-Si断裂,并选用合适的封端剂将其转化成甲基氯硅烷单体.目前,路易斯酸、有机胺、过渡金属元素、活性炭和分子筛等是催化裂解的主要催化剂,各自工艺的操作条件及催化性能迥异.高沸物的裂解率最高可以达到99％以上,但由于生产工艺复杂、操作成本高等问题的限制,严重阻碍了其工业推广与应用.本文归纳了有机氯硅烷高沸物催化裂解材料的研究进展,分别对铝基化合物、有机胺或季铵盐、过渡金属及其化合物、分子筛或活性炭和金属磷酸盐等催化剂展开介绍,概括了以上各类催化剂的研究现状及面临的问题,并对其发展前景进行了合理的分析与讨论,以期为制备出高效、可工业化的有机氯硅烷高沸物裂解催化剂提供参考.     

Preparation of ultrafine Ce-based oxide nanoparticles and their catalytic performances for diesel soot combustion

The ultrafine Ce-based oxide nanoparticles with different element dopings （Zr, Y） were synthesized by the method of mi- cropores-diffused coprecipitation （MDC） using ammonia solution as the precipitation agent. The activities of the catalysts for soot oxidation were evaluated by the temperature-programmed oxidation （TPO） reaction. Ce-based oxides prepared in this study exhibited high catalytic activity for soot oxidation under tile condition of loose contact between soot particles and catalysts, and the catalytic ac- tivity ofultrafine Ce0.gZr0 iO2 nanoparticle for soot combustion was the highest, whose/＂10, Ts0 and Sco2m was 364, 442 ~C and 98.3%, respectively. All catalysts were systematically characterized by means of X-ray diffraction （XRD）, scanning electron microscopy （SEM）, transmission electron microscopy （TEM）, Brumauer-Emett-Teller （BET）, Fourier transform infrared spectroscopy （FT-IR） and UV-Vis diffuse reflectance spectroscopy （UV-Vis DRS）. It was indicated that the MDC method could prepare the ultrafine Ce-bascd oxide nanoparticles whose the crystal lattice were perfect, and the BET surface area and average crystal size of the ultrafine nanoparticles changed with the different element dopings （Zr, Y）. The H2-TPR measurements showed that the ultrafine Ce-based ox- ide nanoparticles with the doping-Zr cation could be favorable for improving the redox property of the catalysts.     

薄层氮化碳光催化还原CO_2性能研究

以氮化碳(g-CN)为原料,采用水蒸汽焙烧剥离法在Ar/H2O氛围下制备薄层氮化碳(Hg-CN),并对其进行XRD、TEM、FT-IR、BET和UV-Vis DRS等表征。结果表明,进行剥离后,H-g-CN比表面积相比剥离前明显增大。H-g-CN的光催化还原CO_2活性大大高于未剥离gCN的活性,光照反应9 h,H-g-CN光催化还原CO_2活性由剥离前的11. 4μmol·g~(-1)提高至24. 6μmol·g~(-1),H-g-CN的CO选择性为91. 2%,未剥离的g-CN的CO选择性为89. 1%,并提出相应的反应机理。     

Synthesis of La_xK_(1–x)CoO_3 nanorod and their catalytic performances for CO oxidation

A series of Lax K1–x CoO3 nanorod oxides with perovskite structure were synthesized by sol-gel method using polyvinyl alcohol(PVA) as additive.These perovskite-type complex oxide catalysts were characterized by the techniques of X-ray diffraction(XRD),infrared(IR),Brumauer-Emmett-Teller(BET) and scanning electron microscopy(SEM).And the results showed that nanorods of La1–x Kx CoO3 perovskite-type complex oxides were fabricated by sol-gel method when the mass concentration of PVA was 4% and the calcined temperature kept at 700 ℃ for 4 h.The catalytic results of CO oxidation showed that the Lax K1–x CoO3 catalysts had high activity.LaCoO3 nanorods exposed more {110} plane than LaCoO3 nanoparticles,which was beneficial to the catalytic oxidation of CO.LaCoO3 nanorods had the best catalytic performance for the oxidation of CO.At 200 oC,the CO conversion could reach 100%.