Through our newly-developed ＂chemical vapor deposition integrated process （ISVD-IP）＇＂ using carbon OlOXlae （t..u2） as me raw matenal and only carbon source introduced, CO2 could be catalytically activated and converted to a new solid-form product, i.e., carbon nanotubes （CO2-derived） at a quite high yield （the single-pass carbon yield in the solid-form carbon-product produced from CO2 catalytic capture and conversion was more than 30% at a single-pass carbon-base）. For comparison, when only pure carbon dioxide was introduced using the conventional CVD method without integrated process, no solid-form carbon-material product could be formed. In the addition of saturated steam at room temperature in the feed for CVD, there were much more end-opening carbon nano-tubes produced, at a slightly higher carbon yield. These inspiring works opened a remarkable and alternative new approach for carbon dioxide catalytic capture to solid-form product, comparing with that of CO2 sequestration （CCS） or CO2 mineralization （solidification）, etc. As a result, there was much less body volume and almost no greenhouse effect for this solid-form carbon-material than those of primitive carbon dioxide.
In this work, a series of Ni-Mo-Mg-O catalysts with mesoporous structure prepared by sol-gel method were investigated for the oxidative dehydrogenation of propane （ODHP）. The techniques of temperature-programmed reduction with H2 （H2-TPR）, N2 adsorption-desolption, Fourier transform infrared spectroscopy （FT-IR）, X-ray diffraction （XRD） and X-ray photoelectron spectra （XPS） were employed for catalyst characterization. It is found that the activity of the catalysts for ODHP increases first and then decreases with the increase of Mo content. The catalyst with a Mo/Ni atomic ratio of 1/1 exhibits the best catalytic activity, which gives the propene selectivity of 81.4% at a propane conversion of 11.3% under 600 ~C and maintains the good catalytic performance for 22 h on stream. This is related not only to its high reducibility and dispersion as revealed by TPR and XRD, but also to the formation of more selective oxygen species on the MoOz-NiO interface as identified by XPS.
Lin WangWei ChuChengfa JiangYuefeng LiuJie WenZaiku Xie
The 12-phosphotungstic heteropolyacid(HPW)was immobilized on the surface of a silica carrier modified by the amine groups of organosilaneγ-aminopropyl triethoxysilane(APTES),and its catalytic performance was investigated for tetrahydrofuran(THF) ring-opening polymerization.This amine-functionalized catalyst exhibited better activity,and the polytetramethylene ether glycol (PTMG)yield was 63.7%.The 12-phosphotungstic heteropolyacid supported on aminopropyl-functionalized SiO2 support (HPW/SiO2-APTES)was reused four times and showed a good maintenance of activity which was better than that of the conventional catalyst HPW supported on SiO2(HPW/SiO2).These results were obtained using infrared spectroscopy,nuclear magnetic resonance spectroscopy,nitrogen adsorption and X-ray diffraction.HPW on the HPW/SiO2-APTES catalyst exhibited higher dispersed state and maintained a more stable structure than that of the HPW/SiO2 sample.
Doping effects of manganese （Mn） on catalytic performance and structure evolution of NiMgO catalysts for synthesis of multi-walled carbon nanotubes （MWCNTs） from methane were investigated for the first time. Addition of Mn in NiMgO catalyst can greatly improve the MWCNTs yield. Mno.2NiMgO catalyst among the tested ones gives the highest MWCNTs yield as 2244%, which is two times higher than that of the catalyst without Mn. The structure evolution, reduction behaviors and surface chemical properties of MnNiMgO catalysts with various Mn contents were studied in detail. It was found that the stable solid solution of NiMgO2 formed in NiMgO catalyst was disturbed by the addition of Mn. Instead, another solid solution of MnMg608 is formed. More amount of Ni can be reduced and dispersed on the catalyst surface to be acted as active sites. Importantly, the changes of Ni content on the surface are correlated with the Ni particle size and the outer diameter of MWCNTs, suggesting the controllable synthesis of MWCNTs over MnNiMgO catalysts.
Mesoporous silica supported Cs2.5H0.5PW12O40 catalysts were prepared by impregnation method, and several silica supports with different pore size were utilized. N2 adsorption, XRD and ICP-AES techniques were utilized to characterize the silica supports and catalysts. XRD results showed that the dispersion of Cs2.5H0.5PW12 was better for the silica support with larger pore size. The catalytic activity results showed that the pore size played important role on the catalyst activity and the molecular weight of PTHF. When Cs2.5H0.5PW12O40 was dispersed on larger pore size silica support, the catalysts showed good performances for the synthesis of PTHE The molecular weight of PTHF product on the sample in which Cs2.5H0.5PW12O40 was dispersed on larger pore support was higher than that on the catalyst with smaller pore support. The leaching amounts of the active components for the supported Cs2.5H0.5PW12O40 catalysts were much lower. After five reaction cycles, there were still good activities and stabilities for the supported Cs2.5H0.5PW12O40 catalysts with larger pore silica supports. These results were much better than those of the supported heteropolyacid H3PW12O40 catalyst.
Xue Mei LiaoWei ChuYang LiFU Dong ZhouaShi Zhong Luo
