Catalytic performance of cement clinker supported nickel catalyst in glycerol dry reforming

The paper reports the development of cement clinker-supported nickel （with metal loadings of 5 wt%, 10 wt%, 15 wt% and 20 wt%） catalysts for glycerol dry （CO2） reforming reaction. XRF results showed that CaO constituted 62.0% of cement clinker. The physicochemical characterization of the catalysts revealed 32-folds increment of BET surface area （SBET） with the addition of nickel metal into the cement clinker, which was also corroborated by FESEM images. Significantly, XRD results suggested different types of Ni oxides formation with Ni loading, whilst Ca3SiO5 and Ca2Al0.67Mn0.33FeO5 were the main crystallite species for pure cement clinker. Temperature-programmed reduction analysis yielded three domains of H2 reduction peaks, viz. centered at approximately 750 K referred to as type-Ⅰ peaks, another peaks at 820 K denoted as type-Ⅱ peaks and the highest reduction peaks, type-Ⅲ recorded at above 1000 K. 20 wt% Ni was found to be the best loading with the highest XG and H2 yield, whilst the lowest methanation activity. Syngas with lower H2/CO ratios （0.6 to 1.5） were readily produced from glycerol dry reforming at CO2-to-Glycerol feed ratio （CGR） of unity. Nonetheless, carbon deposit comprised of whisker type （Cv） and graphitic-like type （Cc） species were found to be in majority on 20 wt%Ni/CC catalysts.     

Nd,Ce和La改性对Ni/SBA-15催化剂在CH4/CO2重整反应中性能的影响

以稀土金属Nd,Ce或La的氧化物为助剂,采用β-环糊精浸渍法对Ni/SBA-15催化剂进行了改性,并运用X射线衍射、N₂吸附-脱附、程序升温还原和热重等手段考察了改性的催化剂在CO₂重整CH₄制合成气反应中的催化性能. 结果表明,Nd等稀土金属氧化物的添加对催化剂孔结构和晶相结构等性质影响不大,但可影响NiO的还原; Nd的添加使NiO与载体之间以Ni-Nd-O形式相互作用,促进了活性组分NiO的还原. 其中,Nd的添加量为5-10 wt%时所制备的催化剂在重整反应中的催化活性最高,且具有很强的抗积碳性能. La和Ce氧化物促进的Ni催化剂也表现出类似的性质和催化性能.     

Chinese Journal of Catalysis Graphical Contents

Chin. J. Catal., 2014, 35: 1911–1916 doi: 10.1016/S1872‐2067(14)60208‐4 Dehydrogenation of primary aliphatic alcohols to aldehydes over Cu‐Ni bimetallic catalysts Tianliang Lu, Zhongtian Du, Junxia Liu, Chen Chen, Jie Xu * Dalian Institute of Chemical Physics, Chinese Academy of Sciences; University of Chinese Academy of Sciences     

Photoassisted Selective Steam and Dry Reforming of Methane to Syngas Catalyzed by Rhodium–Vanadium Bimetallic Oxide Cluster Anions at Room Temperature

Photoassisted steam reforming and dry (CO₂) reforming of methane (SRM and DRM) at room temperature with high syngas selectivity have been achieved in the gas-phase catalysis for the first time. The catalysts used are bimetallic rhodium–vanadium oxide cluster anions of Rh₂VO_1–3⁻. Both the oxidation of methane and reduction of H₂O/CO₂ can take place efficiently in the dark while the pivotal step to govern syngas selectivity is photo-excitation of the reaction intermediates Rh₂VO_2,3CH₂⁻ to specific electronically excited states that can selectively produce CO and H₂. Electronic excitation over Rh₂VO_2,3CH₂⁻ to control the syngas selectivity is further confirmed from the comparison with the thermal excitation of Rh₂VO_2,3CH₂⁻, which leads to diversity of products. The atomic-level mechanism obtained from the well-controlled cluster reactions provides insight into the process of selective syngas production from the photocatalytic SRM and DRM reactions over supported metal oxide catalysts.     

Enhancement of the catalytic performances and lifetime of Ni/γ-Al2O3 catalysts for the steam toluene reforming via the combination of dopants: inspection of Cu,Co, Fe,Mn, and Mo species addition

In this work, the influence of metallic dopant addition in 10 wt % Ni/γ-Al₂O₃ catalyst on the material physico-chemical properties and catalytic activity for the toluene steam reforming was studied. Seventeen doped Ni/γ-Al₂O₃ catalysts were synthesized by the sol–gel process. The aim of this study was to determine which elements were the most suitable for the doping of 10 wt % Ni/γ-Al₂O₃ catalysts. The influence of the dopants was studied through different physico-chemical techniques. It appeared that some dopants showed lower catalytic performances due to high carbon deactivation. On the contrary, some dopants increased the resistance to coking while also improving the catalytic activity. Different mechanisms were proposed to explain these modifications of catalytic behavior. Among all doped Ni/γ-Al₂O₃ catalysts, the samples that combined Mn + Mo or Co + Mo dopants showed the best catalytic performances at 650 °C. Both samples showed high toluene reforming activity and low amounts of carbon deposit.     

Ultrasonication-promoted synthesis of Ni/mayenite for catalytic reforming of biomass tar

Ultrasound-assisted approach was successfully applied for the synthesis of mayenite from calcium and aluminum hydroxides and then subsequently impregnated with Ni by the wet impregnation method. The synthesis was performed with a 13 mm probe-type ultrasound, operating under an acoustic power of 30.5 W and a frequency of 20 kHz. Ultrasound application was studied in detail from a 3^k experimental design, where the variables studied were ultrasound time (10–50 min) and calcination temperature (900–1200 °C). Ultrasound promoted an effective dispersion of the precursors in a short time of 10 min leading to a high conversion to mayenite after calcination at 1200 °C. Ultrasound treatment also had a positive effect on Ni impregnation, increasing the dispersion of the metal in the support and leading to a stronger interaction of nickel-containing species with mayenite support. The use of ultrasound application has proved to be attractive both for catalyst properties and for facilitating catalyst synthesis.     

生物质热化学转化制备生物燃料及化学品

生物质是环境友好的可再生能源.近年来相关研究不断升温,文献报道量激增.本文在现有文献综述及近期报道的基础上,从利用热化学方法由生物质获得燃料油及化学品的角度对各方案进行了归纳、适当补充及简要述评,重点介绍了生物油催化裂解精制、水相重整制备烷烃、超临界水/水热制备化学品3个领域.     

CuZnAl水滑石衍生催化剂上甲醇水蒸气重整制氢Ⅰ. 催化剂焙烧温度的影响

 以类层柱CuZnAl水滑石为前体,经不同温度焙烧制备了一系列甲醇水蒸气重整制氢催化剂. 在250 ℃、 水/甲醇比1.3和重时空速2.5 h-1下的反应结果表明, 600 ℃焙烧的催化剂具有优异的活性和稳定性,而≤500 ℃和≥700 ℃焙烧后的催化剂活性较差. 热重、 X射线衍射、 傅里叶变换红外光谱和程序升温还原分析结果表明, 600 ℃焙烧时水滑石分解较为完全,析出纳米CuO粒子的同时伴生CuAl2O4尖晶石相,进而在反应过程中对金属Cu纳米粒子和ZnO起到良好的隔离和稳定作用. 焙烧温度≥700 ℃时CuO纳米粒子发生二次团聚,同时CuAl2O4尖晶石相大量生成,造成催化活性位减少,活性较低; 而焙烧温度≤500 ℃时水滑石分解不完全,生成 (Cu,Zn)AlxOy(CO3)z复合物且无尖晶石相伴生,造成反应中金属Cu纳米粒子和ZnO聚集,导致催化剂活性较低.     

Kinetic studies of CO2dissociation on supported Ni catalysts

Summary In order to investigate the kinetics of CO₂dissociation on supported nickel catalysts, a novel technique, which can give the surface reaction rate constants with no information on the number of active sites, was developed. It was revealed that CO₂dissociation was more enhanced on TiO₂support than on other metal oxide ones. The activity pattern and activation energies were in good agreement with those obtained by a conventional pulse technique using the number of active sites, suggesting the validity of the present technique for investigating the kinetics of the surface reaction.</o:p>     

湿混法制备甲醇氧化重整制氢CuZnAlZr催化剂

用简易湿混法制备了用于甲醇氧化重整制氢的CuZnAlZr催化剂,与共沉淀法制备的催化剂比较,结果表明,湿混法制备的催化剂具有相当的中高温活性和略低的低温活性,有较高的CO2选择性。XRD、TPR、TG-DSC等表征结果显示,湿混法制备的催化剂中铜组分易于向表面迁移和富集,并可能与氧化铝作用生成铜铝复合氧化物,具有了更高的Cu分散度和Cu0比表面浓度。湿混法制备的催化剂对甲醇氧化重整反应有较好的稳定性,经100 h的连续反应,在275 ℃时甲醇转化率在90％以上,重整气中氢气体积分数大于60％,CO2选择性接近99％。