Application of Sol-Gel Method to Preparation of Ultra-Uniform Co-Based Catalysts for Fischer-Tropsch Reaction

Uniformly dispersed Co/SiO₂ catalysts (10–60 wt% on metal basis) were prepared by the sol-gel method, and used for the Fischer-Tropsch (F-T) synthesis in slurry phase at 503 K and 1 MPa in a flow of synthesis gas (H₂/CO = 2/1, W/F = 10 g-catal·h/mol). The catalysts were characterized by temperature-programmed reduction (TPR), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), and chemisorption. Although CO conversion over the unpromoted catalysts prepared by the sol-gel method was lower than the conventional catalysts prepared by impregnation, the catalytic activity of the former catalysts was more stable than the latter catalysts. The conversion was improved drastically, when 0.01–1 wt% of Ir or Ru (on metal basis) was added to the catalysts prepared by the sol-gel method. The TPR and XPS spectra and the H₂ chemisorption revealed that the noble metal addition was responsible for the reduction of Co particles in the catalysts. It is supposed that the durability of the promoted catalysts prepared by the sol-gel method was ascribed to the high dispersion of Co particles stabilized on the catalyst surface.     

Cu-Co合成醇催化剂制备方法的研究

在一般金属催化剂上，由CO和H2选择合成高级醇是合成气化学的重要研究方向［1－4］．IFP在1982年提出的＊u－C。催化剂至今还是非常重要的体系＊’］．它的特点是液体产物中除水外，都是直链伯醇，CI醇占较大的分数·但是，这类催化剂存在热稳定性差，活性低的缺点·为了改善催     

Experimental derivation of Auger transition probabilities from X-ray excited Auger electron spectra in XPS

Auger transition probabilities were experimentally derived from dominant XAES and related XPS peaks observed in XPS spectra. Some values of derived probabilities were higher than 1, because of addition or subtraction of background signal from the XAES or/and XPS peak intensity. However, the probabilities obtained are recognized to be useful for practical quantification by XAES and AES.     

TPR and XPS studies of NaCl modified VCe0.2Cu0.8catalysts for direct propylene epoxidation

Summary NaCl promoted VCe_xCu_1-xO catalysts were characterized by TPR and XPS. The catalytic activities were correlated with TPR results. XPS results implied that NaCl probably acted as an electronic promoter.     

甲醇含成Cu-Mn/SiO_2催化剂的研究

对浸渍法制备的Cu－Mn／SiO2催化剂进行了甲醇合成的活性评价，同时用XPS、Auser、N2O分解，TPR等技术对催化剂进行了表征．结果表明，在双组份催化剂中，工作态催化剂表面主要存在Cu（O）．催化反应可能通过Cu…O－Mn氧桥的长程诱导交换作用，使Cu带部分正电荷，这有利于CO与H2的吸附和活化，从而提高甲醇合成的收率．     

浸渍溶剂对Fe／AlPO_4－5催化剂性能的影响

浸渍溶剂对Ｆｅ／ＡｌＰＯ_４－５催化剂性能的影响马静红，范彬彬，李瑞丰，曹景慧（太原工业大学精细化工研究所，太原０３００２４）关键词Ｆｅ／ＡｌＰＯ_４－５催化剂，制备方法，浸渍溶剂，ＣＯ加氢反应ＡＩＰＯ４－５是一种新型的分子筛，其独特的晶体结构和表面选...     

Experimental derivation of Auger transition probabilities from X-ray excited Auger electron spectra in XPS

Auger transition probabilities were experimentally derived from dominant XAES and related XPS peaks observed in XPS spectra. Some values of derived probabilities were higher than 1, because of addition or subtraction of background signal from the XAES or/and XPS peak intensity. However, the probabilities obtained are recognized to be useful for practical quantification by XAES and AES. Received: 6 April 1999 / Revised: 25 June 1999 / Accepted: 6 July 1999     

Effect of Mg/Al atom ratio of support on catalytic performance of Co-Mo/MgO-Al2O3 catalyst for water gas shift reaction

Co-Mo-based catalysts supported on mixed oxide supports MgO-Al₂O₃ with different Mg/Al atom ratios for water gas shift reaction were studied by means of TPR, Raman, XPS and ESR. It was found that the octahedral Mo species in oxidized Co-Mo/MgO(x)-Al₂O₃ catalyst and the contents of Mo⁵⁺, Mo⁴⁺, S²⁻ and S²⁻₂ species in the functioning catalysts increased with increasing the Mg/Al atom ratio of the support under the studied experimental conditions. This is favorable for the formation of the active Co-Mo-S phase of the catalysts. Catalytic performance testing results showed that the catalysts Co-Mo/MgO-Al₂O₃ with the Mg/Al atom ratio of the support in the range of 0.475–0.525 exhibited optimal catalytic activity for the reaction.     

稀土金属盐促进的Mo-Co-K硫化物基催化剂用于合成气选择性制乙醇等低碳混合醇

采用超声法在非水溶剂介质中制备了稀土金属La盐等促进的硫化钼基催化剂,考察了其CO加氢选择性合成乙醇等低碳混合醇的催化性能.在3.0MPa,330℃和H2/CO(体积比)=2.0的反应条件下,La促进的催化剂表现出较Mo-Co-K硫化物基催化剂更高的催化活性,CO转化率和产物中乙醇的分布可分别达到17.2%和53.4%.扫描电镜、透射电镜、X射线衍射和光电子能谱等表征结果表明,稀土金属La盐的加入改善了Mo-Co-K硫化物基催化剂的外观形貌和电子结构,对提高催化活性和乙醇的分布起到重要的作用.     

Structure, reduction and catalytic properties of perovskite-like LaMn1?xNixO3 oxides

A series of LaMn_1–xNi_xO₃ (x=0–1.0) catalysts with perovskite structure has been prepared. The relationship among composition, crystal structure, reducilibity and the catalytic activities for CO oxidation has been investigated. XRD showed that samples for x=0.0–0.4 and x=0.8–1.0 had rhombohedral symmetry, and then pseudo-cubic symmetry for x=0.5–0.8. Research by IR and TPR indicated there were interactions between Mn and Ni coexisting in the B site of LaMn_1–xNi_xO₃. The oxidation activities of the catalysts were also measured.     

铜基甲醇合成催化剂的失活研究

选用了两个化肥厂的失活甲醇合成催化剂,采用ＸＲＤ、ＳＥＭ、ＳＥＭ－ＥＤＳ、ＴＥＭ、ＸＰＳ、ＴＲＰ、ＣＯ－ＴＰＤ和化学吸附等方法对催化剂进行比较测试。结果表明,硫中毒、积炭、铜粒长大和杂质金属沉积等是造成甲醇合成催化剂失活的因素。由于某一种或几种因素都导致催化剂活性表面积的降低,对反应物ＣＯ吸附量减少,或造成催化剂对ＣＯ吸附能力的降低,从而降低合成甲醇反应的活性。硫中毒和铜粒长大是普遍存在的最主要因     

XPS characterization of the reduction and synthesis behaviour of Co/Mn oxide catalysts for Fischer-Tropsch synthesis

Summary The surface composition of Co/Mn oxide catalysts after calcination, reduction and during CO hydrogenation experiments were investigated by XPS. The bulk changes during reduction were studied by Temperature Programmed Reduction (TPR). The calcined catalysts showed Co/Mn oxides of different compositions in their surfaces. The Co surface concentration, of the catalysts with high Co content, decreased after calcination compared to the bulk composition, but after reduction the bulk concentration was almost reached again. The catalysts with low Co content showed no decrease in the surface concentrations after calcination. Significant differences in surface concentrations for the catalysts Co20 and Co5 were observed by analysing the Co 2p and 3p levels, respectively; these can be explained by an internal reduction model. After reduction the sample Co100 was completely reduced to metallic cobalt. In the manganese-containing catalysts, after in-situ reduction, Co³⁺ and Co²⁺ were found; all manganese was reduced to Mn²⁺. A comparison of the results of the in-situ reduction and the TPR profiles led to the development of a so called internal reduction model. This model assumes migration of the Co²⁺ ions to the reduction front in inner layers of the catalysts, where they will be reduced to metallic cobalt; this is enriched in the bulk and cannot be found at the surface. The manganese matrix stabilizes the surface oxide layer so that all catalysts exhibited Co/Mn spinels in the surface. Synthesis experiments in the reaction chamber of the XPS apparatus did not lead to changes of the catalyst surfaces as a function of the reaction pressure, synthesis time or synthesis gas composition. The differences in the synthesis behaviour observed for the catalysts must be due to other effects, (i.e. a change in adsorption of hydrogen connected with a change in hydrogenation activity or the different cobalt concentrations).     

The Effects of M2O3 on Stabilizing Monocopper over the Surface of Cu-ZnO-M2O3 Catalysts for Mathanol Synthesis

The effects of M₃O₃ (M = Al, Sc etc.) in Cu-ZnO-M₂O₃ catalysts on methanol synthesis at low pressure were studied with ESR, XPS and TPR spectroscopy. The results of ESR showed that the generation of monovalent cationic defects was because the valence state and electronic charge on the ZnO lattice lost their balance as M³⁺ doped into ZnO. The induced effect by Sc³⁺ is stronger than that by Al³⁺. The results of XPS and TPR indicated that the amount and stabilization of Cu⁺ on the surface of reduced copper-based catalyst and its catalytic activity were affected by the monovalent cationic defects on the surface of ZnO.     

含Y或La助剂的CuO／ZrO2合成甲醇催化剂的性能和结构研究

通过ＣｕＯ／ＺｒＯ２及含Ｙ或Ｌａ助剂的ＣｕＯ／ＺｒＯ２催化剂对ＯＣ／Ｈ２合成甲醇性能的研究，发现稀土助剂能有效地提高该催化剂的活性。ＸＲＤ结果说明，ＣｕＯ｜ＺｒＯ２中加入Ｙ或Ｌａ助剂可使氧化铜处于较高的分散状态。ＴＰＲ结果揭示ＣｕＯ／ＺｒＯ２催化剂中存在着在室温就很容易被氧人的铜，它在催化剂中含量的增加导致催化剂活性的提高，是关切的活性组份。助剂的加入使这种易被氧化的铜含量增加。ＸＰＳ表面分析结果     

沉淀方法对FeMnCu/ZnO合成低碳醇催化剂性能的影响

以分步连续沉淀法和共沉淀法制备了一系列FeMnCu/ZnO复合氧化物合成低碳醇催化剂，对其CO加氢合成低碳混合醇的反应性能进行了考察，并用ICP、XRD、BET、H2-TPR对其结构进行了表征。结果表明，沉淀方法不同对催化剂的催化性能有较大的影响。在T503K、P=8.0MPa，GHSV=8000h－1，H2/CO＝2(体积比)的条件下, 分步沉淀法制备的FeMnCu/ZnO催化剂醇的收率和C2+OH的质量分数均高于共沉淀法制备的催化剂。其中“Fe atop Cu”催化剂醇的收率最高，达到0.26g/mLcat·h，同时“Fe atop Cu”催化剂C2+OH的质量分数也最高，可达31.72%。XRD研究表明，分步沉淀法制备的催化剂促进了CuO和ZnO的分散，提高了催化剂的催化性能。BET测试结果表明，分步沉淀法有扩孔的作用，有利于长链醇的生成。TPR研究发现，共沉淀法制备的催化剂Cu物种较难还原，这是共沉淀催化剂合成醇性能较低的原因之一。     

Effect of elemental molar ratio on the synthesis of higher alcohols over Co-promoted alkali-modified Mo_2C catalysts supported on CNTs

A series of molybdenum carbide catalysts promoted by potassium and cobalt,supported on carbon nanotubes(CNTs) were prepared by carbothermal hydrogen reduction method using CNTs as a carbon precursor.Firstly,molybdenum and cobalt were loaded by co-precipitation method,and then potassium and additional molybdenum were impregnated to previous resultant.Different Mo/Co and K/Co molar ratio were used in catalyst synthesis.All the catalysts were characterized by ICP,BET,TEM,TPR,XRD and XPS,and the catalysts performances for higher alcohols synthesis(HAS) were investigated in a fixed-bed micro-reactor.The maximum selectivity to higher alcohols(C2+OH) was obtained at Mo/Co and K/Mo molar ratios of 1.66 and 0.6,respectively.XRD results confirmed the formation of K-Mo-C site and Co3Mo3 C phase that might play important role in producing C2+OH.     

Synthesis of hydrocarbons and alcohols from CO and H2 in the presence of CO-Rh catalysts

Catalysts of 4.5% Co- 0.1% Rh- 5:10% Cu/TiO ₂ display high activity in the synthesis from CO and H₂ of a mixture of hydrocarbons and alcohols at 250–300°C and pressures of 0.1–6.0 MPa; these catalysts are more selective than traditional Co catalysts with respect to alcohol formation.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 8, pp. 1707–1709, August, 1990.     

Tungsten/Alumina Catalysts: Effect of H3PW12O40 Countercation on Surface Properties and Hydrodesulfurization Activity

H₃PW₁₂O₄₀ heteropoly acid (HPW₁₂) and its Co, Fe, Ni salts supported on alumina have been used to model hydrodesulfurization catalysts of different activity. All catalysts revealed a promoting effect of the countercation in thiophene hydrodesulfurization, that of the nickel cation being the highest. The catalysts were characterized by measurements of surface area, HDS activity, TPR, FTIR, and DR spectra. IR spectra confirmed an effect of the countercation on the phase composition of the supported heteropoly compounds. 12-Tungstoaluminate heteropoly anions and coordinately unsaturated anions of HPW₁₂ were detected in the IR spectra of the catalysts. The hydrotreating activity of the catalysts was proportional to the amount of hydrogen consumed in the range 20–500°C during TPR.     

磷含量对NiMo/γ-Al_2O_3催化剂活性相结构的影响

采用程序升温还原(TPR)、高分辨透射电镜(HRTEM)和X射线光电子能谱(XPS)表征手段对共浸渍法制备的不同磷含量NiMo/γ-Al2O3催化剂进行了表征,研究了磷含量对NiMo/γ-Al2O3催化剂活性相结构的影响。TPR研究表明,磷能够减少四面体配位Mo物种的数量,增加八面体配位Mo物种的数量,促进高活性Ⅱ型"Ni-Mo-S"活性相的形成。HRTEM研究表明,随磷含量的增加,MoS2颗粒堆积层数增加,催化剂的加氢选择性提高;适量磷能够增加边角位有效Mo原子的分散度(fMo),增加催化剂表面加氢脱硫(HDS)和加氢脱氮(HDN)活性位的数量。上述结论得到了XPS表征的证实:适量磷增加了催化剂表面Mo原子浓度、提高有效助剂比率(PR)和提升比率(Ni/Mo),相应催化剂表现出最高的HDS和HDN活性;但过高磷含量能够引起MoS2颗粒过度堆积,片层长度过长,导致活性位数量减少,催化活性降低。     

CO2加氢合成甲醇的超细Cu-ZnO-ZrO2催化剂的表征

采用原位顺磁共振（ＥＰＲ）、原位Ｘ射线光电子能谱（ＸＰＳ）和程序升温还原（ＴＰＲ）等手段,对ＣＯ２加氢合成甲醇用的不同粒度的超细Ｃｕ－ＺｎＯ－ＺｒＯ２催化剂各组分的相互作用进行了研究。结果表明,ＺｒＯ２的加入改变了催化剂的表面结构和配位状态,增加了活性组分的分散度,提高了催化剂的稳定性。实验还发现,催化剂的粒度对各组分的相互作用有着重大的影响,催化剂的粒度较小时,Ｃｕ＾２＋主要以团簇的形式存在,易