Methanation of syngas over coral reef-like Ni/Al_2O_3 catalysts

Coral reef-like Ni/Al2O3 catalysts were prepared by co-precipitation of nickel acetate and aluminium nitrate with sodium carbonate aqueous solution in the medium of ethylene glycolye.Methanation of syngas was carried out over coral reef-like Ni/Al2O3 catalysts in a continuous flow type fixed-bed reactor.The structure and properties of the fresh and used catalysts were studied by SEM,N2 adsorption-desorption,XRD,H2-TPR,O2-TPO,TG and ICP-AES techniques.The results showed that the coral reef-like Ni/Al2O3 catalysts exhibited better activity than the conventional Ni/Al2O3-H2O catalysts.The activities of coral reef-like catalysts were in the order of Ni/Al2O3-673>Ni/Al2O3-573>Ni/Al2O3- 473>Ni/Al2O3-773.Ni/Al2O3-673-EG catalyst showed not only good activity and improved stability but also superior resistance to carbon deposition,sintering,and Ni loss.Under the reaction conditions of CO/H2(molar ratio)=1:3,593 K,atmospheric pressure and a GHSV of 2500 h-1,CH4 selectivity was 84.7%,and the CO conversion reached 98.2%.     

Magnesia Binder Preparation from Local Natural and Technogenic Raw Materials

The preparation of magnesia binders based on natural and technogenic mineral was the result of the research. The obtained magnesia binders possess the increased flexural and compressive strength which values are close to ones of natural materials. High flexural and compression strengths are associated with the features of the hardened caustic dolomite containing magnesium oxyhydrochlorides which crystallize as a fiber. The fibrous crystals not only increase the cement strength, but also act as a reinforcing material. The resulting magnesia binder does not require a moist environment at hardening. It is characterized by decorativeness and ecological compatibility, has a neutral hardening product composition.     

Hydrogenation of cinnamaldehyde over bimetallic Au-Cu/CeO2 catalyst under a mild condition

Bimetallic Au_xCu_y/CeO₂ (x/y=3/1, 1/1, and 1/3) catalysts were prepared by direct anion exchange (DAE), following impregnation (IMP) methods, and used for selective hydrogenation of cinnamaldehyde. The effects of pretreatments, such as calcination or reduction on the catalytic activities of these catalysts were investigated. XRD and HRTEM showed that for the reduced catalysts, there is the formation of an Au-Cu alloy. HAADF-STEM displayed that reduction pretreatment leads to a very homogenous distribution of Au and Cu on the external catalyst surface. Reaction parameters, such as CAL concentration, the stirring speed, nature of the solvent influence the catalytic activities. Pretreatments lead to a major effect on CAL conversion and HCAL selectivity. Catalysts Au_xCu_y/CeO₂pretreated under reduction display higher CAL conversion and HCAL selectivity than that of under calcination mainly due to the synergistic effect resulting in a formation of Au-Cu alloy.     

固体超强酸SO2-4/ZrO2的制备及其催化性能研究

以氧氯化锆为锆原,氨水为沉淀剂,硫酸溶液为浸渍液,通过沉淀-浸渍法制备SO2-4/ZrO2(SZ)酯化催化剂,其结构经BET、X-射线衍射(XRD)、傅立叶变换红外光谱(FT-IR)及扫描电子显微镜(SEM)表征.结果表明:随着焙烧温度升高,催化剂的比表面积依次降低,孔径增大,氧化锆的晶态由无定形态转化为四方晶态再转化为单斜晶态;于600℃焙烧时,催化剂形成的S=O键红外吸收峰最强;于700℃焙烧时,催化剂结构被破坏.在丙烯酸与十八醇的酯化反应中对催化剂进行活性测试.结果表明:600℃焙烧的催化剂产率最高(96.4%).     

焙烧温度对Ni/La(Ⅲ)催化剂氢解山梨醇制备低碳二元醇性能的影响

采用水热法合成了纳米棒状La(OH)₃载体,通过湿式浸渍方法制备了10%Ni/La(Ⅲ)负载型催化剂,考察了500~800℃不同焙烧温度对于催化剂氢解山梨醇制备低碳二元醇的影响,结合XRD、SEM/EDS、BET、H₂-TPR-MS、CO/CO₂-TPD-MS、TG和ICP-AES等表征手段对Ni/La(Ⅲ)催化剂的构效关系进行了分析。结果表明,Ni/La(Ⅲ)催化剂表现出高的氢解反应活性,在较低的焙烧温度下(500℃)催化剂主要以NiO/La₂O₂CO₃结构形式存在。随着焙烧温度的升高,NiO/La₂O₂CO₃逐渐向La₂NiO₄-La₂O₃进行转变。碱性是影响不同催化剂活性的决定因素,高的焙烧温度促进了催化剂中强碱性位的生成,显著提高了氢解反应活性,但对液体产物的选择性无明显影响,在220℃、4MPa H₂、1.5h的条件下,山梨醇完全转化,低碳二元醇的产率可达到53%。低的焙烧温度则增加了催化剂的水热稳定性。催化剂的失活主要归结于活性金属粒子在水相反应中从载体表面脱落而发生团聚,降低氢解反应活性。     

Transesterification of canola oil over Li/Ca-La mixed oxide catalyst: Kinetics and calcination temperature investigations

In this research, a solid 1%Li/Ca-La mixed oxide catalyst was prepared using co-precipitation method followed by wet impregnation. The prepared catalyst was used in the transesterification reaction of canola oil and methanol for biodiesel synthesis. The effects of calcination and reaction temperatures were investigated on the activity of the catalyst. In addition, rate of the reaction was studied through a kinetic model for which parameters were determined. Surface properties and structure of the catalyst were characterized through the powder X-ray diffraction (XRD), thermogravimetry/derivative thermogravimetry (TG/DTG), and Fourier transform infrared spectroscopy analysis. All these emphasized that the performance of the catalyst corresponded to the generation of the active sites and their thermal activation.     

焙烧温度对Pd-Cu/凹凸棒土CO常温催化氧化性能的影响

以凹凸棒土(APT)作载体,采用等体积浸渍法制备了Pd-Cu/APT催化剂,以CO氧化为探针反应,在连续流动微反装置上,考察了焙烧温度对催化剂CO常温催化氧化性能的影响。通过N2-物理吸附、XRD、TG、FT-IR和H2-TPR等手段对催化剂的结构和性质进行了表征。结果表明,随焙烧温度升高,Pd-Cu/APT中载体逐步脱水,进而引起催化剂结构和织构变化,其中,Cu物种由Cu(OH)Cl逐渐向CuO转变,同时,高分散的Pd物种与Cu物种间相互作用先增强后减弱。经300℃焙烧的催化剂比表面积大,Cu物种以Cu(OH)Cl形式存在,且具有良好的分散状态,与Pd物种之间产生较强的相互作用,显著提高了其还原性能。在空速6 000 h-1、CO体积分数0.5%、水蒸气体积分数3.3%的反应条件下,常温可将CO完全转化800 min以上。焙烧温度高于或低于300℃均引起CO常温催化氧化性能的下降。     

焙烧温度对Ni/γ-Al_2O_3还原条件及催化甲苯水蒸气重整反应的影响

研究了焙烧温度对Ni/γ-Al2O3还原条件及催化甲苯水蒸气重整反应的影响。结果表明,焙烧温度对催化剂的还原条件及性能具有重要影响。700℃焙烧的催化剂在680℃的反应温度下表现出良好的反应性能,在不进行预还原的情况下仍保持了很高的催化活性及稳定性,其中,甲苯转化率达99%。并使用BET、XRD、TG-DTG等表征方法对反应前后的催化剂进行表征,随着焙烧温度的升高,催化剂比表面积降低、总孔容减小、平均孔径增大、镍与载体的结合程度逐渐增强、NiAl2O4含量逐渐增多,这是焙烧温度影响催化剂还原条件的主要原因。最后通过TEM、XPS对700℃焙烧的催化剂的结构进行了进一步的分析。     

PDP用蓝色荧光粉SrMgAl10O17:Eu2+的制备与发光性能研究

以Eu2O3(AR)、Sr(NO3)2(AR)、Mg(NO3)2.6H2O(AR)、Al(NO3)3.9H2O(AR)为原料,NH4HCO3为沉淀剂,采用化学共沉淀法制备前驱物,经一次煅烧制备出蓝色荧光粉SrMgAl10O17:Eu2+。用X射线衍射仪、荧光分光光度计分别测试样品结构与发光性能。结果表明:在1 200℃下煅烧即可生成六方结构的SrMgAl10O17:Eu2+,比高温固相法煅烧温度低300℃;其发射光谱最强峰在470 nm,Eu2+的最佳掺杂摩尔分数为10%;选用H3BO3为助熔剂,可提高粉体发光强度,其最佳质量分数为1.5%。     

柠檬酸凝胶法合成Ni-ZrO_2催化剂及其低温浆态床甲烷化性能研究

采用柠檬酸凝胶法制备不同温度焙烧的Ni-ZrO_2催化剂,考察了催化剂的表面性质和结构对低温浆态床CO甲烷化性能的影响.结果表明,随着焙烧温度的升高,催化剂的比表面积和孔容逐渐减小,金属Ni分散度先增加后减小,Ni晶粒先减小后增大.450℃焙烧的Ni-ZrO_2催化剂金属Ni分散度最高、Ni物种与载体ZrO_2的相互作用最强、对反应物CO分子的吸附作用适中且脱附量大,在260℃、1.0 MPa和H_2/CO摩尔比为3的条件下,CO转化率达到61.6%,且催化活性稳定,750℃焙烧的催化剂反应后金属Ni团聚且晶粒长大,导致催化剂失活.