加氢反应催化剂的改进

正本发明涉及到催化剂,制造催化剂的过程以及应用此类催化剂的化学工艺。该催化剂优先用于转化醋酸和醋酸乙酯成乙醇。催化剂包括挤出的改性和一种贵金属。制造催化剂的过程包括改进催化剂,挤出催化剂,以及将贵金属浸渍在催化剂上。     

葡萄糖加氢催化剂研究现状及发展趋势

介绍了葡萄糖加氢生产山梨醇用催化剂的国内外研究和发展现状;分析了各类催化剂的葡萄糖催化加氢性能和使用条件,指出了各类催化剂的优缺点;提出了催化剂的发展趋势是由Raney镍催化剂向改性多元Raney镍催化剂发展,由多元改性Raney镍催化剂向负载型贵金属催化剂发展,由晶态催化剂向非晶态催化剂发展。     

合成间同立构PS用单中心催化剂的研究进展

综述了茂金属催化剂和非茂钛催化剂合成间同立构聚苯乙烯的研究进展,其中,茂金属催化剂主要包括茂钛催化剂、单茂钛催化剂、茚钛催化剂、双核金属催化剂及负载型催化剂等。今后的研究重点是负载型茂金属催化剂和非茂钛催化剂,单中心催化剂将对合成间同立构聚苯乙烯的工业化发展发挥重要的作用。     

酯化反应催化剂研究新进展

传统的酯化反应催化剂如浓硫酸、磷酸、对甲苯磺酸虽然具有较高的催化活性,价廉易得,但存在副反应多、对设备腐蚀严重、能耗大、反应废液处理复杂等缺点。因此,寻找可代替传统催化剂的新型酯化催化剂势在必行。介绍了近年来酯化反应中催化剂研究的进展情况,对相转移催化剂、室温离子液体催化剂、无机盐催化剂、树脂类催化剂、分子筛催化剂、杂多酸催化剂、固体超强酸催化剂等不同催化剂的特点进行了总结,比较了各类催化剂使用过程中的优缺点。提出了酯化反应催化剂未来的研究方向,主要在于开发高效环保型绿色催化剂。     

裂化催化剂失活动力学及平衡催化剂活性模型

基于催化剂全混流流动状态和呈指数形式的催化剂年龄概率密度函数,经催化剂失活动力学方程推导,确定了关联催化剂碳含量、金属沉积量、催化剂置换率、再生器温度和水蒸气分压的平衡催化剂活性或微反活性模型方程。对工业催化裂化装置操作数据进行模拟计算,确定了催化剂失活模型参数,建立了具有较高模拟计算精度的裂化催化剂失活动力学和平衡催化剂活性模型。比较模型参数大小可知,V沉积对催化剂活性的影响最大,其次是Ni和Fe,Na的影响最小。模型预测结果表明,随着平衡催化剂金属沉积量或碳含量减少,催化剂单耗增大,平衡催化剂活性或微反活性逐渐增大。适当降低再生器温度和催化剂藏量有利于提高平衡催化剂活性。     

烯酸加成酯化反应催化剂研究进展

烯烃与羧酸在催化剂作用下进行加成反应生成羧酸酯,这一反应属于原子经济反应,越来越受到研究者的关注。综述21世纪以来烯烃与羧酸加成酯化反应催化剂的研究进展,包括磺酸类催化剂、离子交换树脂催化剂、杂多酸化合物催化剂、离子液体催化剂、沸石分子筛催化剂和过渡金属化合物催化剂等,对各类催化剂活性进行比较,并展望烯酸加成酯化反应催化剂的研究方向。     

新型孔雀石型1,4-丁炔二醇催化剂的开发

英威达1,4-丁二醇(BDO)生产工艺中1,4-丁炔二醇合成催化剂,采用无载体的孔雀石型铜铋催化剂,使用过程催化剂容易粉化,催化剂寿命只有2个月左右,本论文开发的新型孔雀石型催化剂,采用了惰性组分作为载体,经过5kg级催化剂评价达到了工业应用的需要,催化剂的活性、选择性与目前无载体的铜铋催化剂性能相当,催化剂的寿命明显高于现有无载体催化剂的寿命,中试评价催化剂连续使用100天以上,较原有催化剂寿命提高40%以上,该催化剂的工业化应用将使现有工业装置每年的催化剂的更换次数由6次降低到3～4次,整个装置的BDO产量提高5%以上。     

选择性催化还原脱硝催化剂的研究进展

选择性催化还原（SCR）是目前控制氮氧化物排放的主要技术,该技术具有选择性好、脱硝效率高、不造成二次污染等优点。本文对SCR技术及其催化剂进行了综述,重点介绍了钒钛催化剂、贵金属催化剂、金属氧化物催化剂及沸石分子筛型催化剂的研究进展,并对国内外脱硝催化剂的工业化现状及催化剂的影响因素进行了分析,最后指出我国脱硝催化剂的发展应以提高催化剂寿命、开发新型催化剂（以复合金属氧化物催化剂和新型钒基催化剂为主）及新工艺为方向进行。     

糖醇氢解催化剂研究进展

催化剂研究是糖醇氢解体系的核心。综述糖醇催化氢解的催化剂研究进展,介绍贵金属催化剂、镍系催化剂、铜系催化剂、双金属催化剂以及其他催化剂在糖醇氢解反应中的应用,分析各类催化剂的优缺点,并对催化体系研究方向进行展望。     

直链烯烃骨架异构化催化剂的研究进展

文章概述了烯烃骨架异构化催化剂,包括卤化物催化剂、氧化物催化剂和分子筛催化剂。与卤化物催化剂和氧化物催化剂相比,分子筛催化剂表现出了优异的直链烯烃骨架异构化性能。     

机制砂岩性与级配对混凝土抗硫酸盐侵蚀性能的影响

为了探究不同岩性、不同级配机制砂对混凝土性能的影响,对三种不同岩性机制砂混凝土及天然河砂混凝土的工作性和抗压强度进行研究。此外,对比分析了四种混凝土在干湿循环制度下的抗硫酸盐侵蚀性能。结果表明,天然河砂混凝土的工作性优于机制砂混凝土,钙质机制砂混凝土的工作性略好于硅质机制砂混凝土。机制砂混凝土的抗压强度优于天然河砂混凝土,在硫酸盐侵蚀循环作用下的力学性能变化趋势与天然河砂混凝土基本一致。在相同级配条件下,机制砂混凝土的抗蚀系数高于天然河砂混凝土;机制砂岩性并不会对混凝土抗硫酸盐侵蚀性能带来负面影响。级配良好的机制砂可以增强混凝土抗压强度和抗硫酸盐侵蚀性能。     

Functional properties of proteins in foods

The measurement of functionality of protein food ingredients has developed somewhat haphazardly, probably due to the wide range of proteins used as ingredients and the diversity of foods. Studies of the physiochemical properties of proteins should enable prediction of a proteins response to process environments and prove more fruitful than many of the empirical measurements of functionality. The effects of pH, salt type and concentration on the phase behaviour of the oilseed globulin and arachin, demonstrates the complexity of protein solubility and the inadequacies of simple tests that have arisen. Studies of the effects of salts and conditioning on meat fibres, coupled with measurement of the location of water in pellets from water holding tests enable the latter to be applied with increased confidence. Comparison of the endothermic transitions observed on heating with the development of storage and loss moduli allow the contributions of domains of skeletal muscle myosin to gel structure to be investigated.     

Aggregation pheromone system of adult gregarious desert locust schistocerca gregaria (forskal)

Six electrophysiologically active aromatic compounds, viz., anisole, benzaldehyde, veratrole, guaiacol, phenylacetonitrile, and phenol, were identified in the volatiles of older-adult male desert locust. Young adults and females of all age groups produced none or only trace quantities of these compounds. Comparison of the aggregation responses of young and older adults to the crude, older-adult, volatile extract and different synthetic blends of the six compounds showed that the aggregation pheromone system of the adult gregarious locust consists of phenylacetonitrile, guaiacol, phenol, and benzaldehyde. Like the crude volatile extract of older males, neither the synthetic blend of the six compounds nor the adult pheromone blend evoked any significant aggregation responses from nymphs. These results confirm our previous report of sexual differentiation in the production of adult aggregation pheromone in the desert locust and of the evidence of two distinct aggregation pheromone systems in the two stages of the insect.     

Molecular mechanics modelling of interfacial energy and flexibility on cellulose

Molecular mechanics modelling is used to calculate the energies of interaction, hence the molecular level energy of adhesion at the interface with crystalline cellulose I of three different photopolymerizable primers and of a polyester varnish at the interface with the primer/cellulose assembly. The energy of interactions for just one of the primers with the statistically most common conformation of amorphous cellulose has also been obtained for comparison. Experimental results of adhesion by a standard peel test and by thermomechanical analysis, in which the effect of viscoelastic energy dissipation by crack tip propagation has been respectively minimized or is not present, hence in which the energy of interfacial interaction is nothing else but the work of adhesion, correlated well with the energies of interaction calculated by molecular mechanics. An equation correlating the energy of interaction at each finish/cellulose interface with the deflection derived by thermomechanical analysis, and with the number of internal bond rotational degrees of freedom as well as the degree of networking of the finish, has been derived and is presented. A relationship between the intrinsic fracture energy Go and the molecular mechanics-derived energy of interaction at the interface equating this to the square of the work of adhesion is obtained and is presented.     

Distribution of birch (Betula SPP.), willow (Salix SPP.), and poplar (Populus SPP.) secondary metabolites and their potential role as chemical defense against herbivores

Isoprenoids and phenolics, major metabolites of important browse species, are reviewed in regard to concentrations, distribution within tissues, and between species. Seasonal variation of specific substances and changes with age of the plant are also considered. The distribution of substances may affect food selection and feeding behavior of animals. Wild mammalian herbivores tend to avoid plant parts rich in these substances, in spite of high nutritional content of the plant tissue. Possible mechanisms for defense by plants against depredation by mammalian herbivores are discussed within the framework of the plants' biochemistry.     

Sr改性Cu催化剂的果糖加氢制备甘露醇性能

使用共沉淀法制备负载Cu催化剂。通过添加碱土金属Sr，对Cu催化剂进行了改性，以提高Cu催化剂在果糖加氢制备甘露醇过程中的活性和选择性。采用ICP-MS、TEM、XRD、H₂-TPR、XPS和CO₂-TPD等对所制备的催化剂进行了系统表征。结果表明：Sr的添加能增大催化剂的比表面积，促进活性组分Cu的分散，从而提高了催化剂的活性，并且增加了催化剂的碱性，使果糖优先形成β-呋喃糖中间体，从而提高了甘露醇的选择性。在果糖浓度为1.1 mol·L^-1、催化剂用量为反应物质量的6%、反应温度为373 K、反应氢压为4.0 MPa、Cu/Sr原子比为7∶1的反应条件下，果糖转化率为99%，甘露醇的选择性为79%。催化剂循环使用了20次，其催化稳定性基本保持不变。     

接触式机械密封界面泄漏机理研究的关键科学问题

密封界面的泄漏机理是机械密封研究与应用的焦点问题之一,涉及泄漏通道表征、粗糙表面的接触力学模型、界面微观形貌变化以及介质流体在泄漏通道中的流动阻力等问题。回顾了近几十年国内外接触式机械密封泄漏通道模型的研究,深入分析了G-W模型、M-B模型和Persson模型3种粗糙表面接触力学模型的贡献和存在的问题,提出了一种基于逾渗理论的泄漏通道新模型;探讨了密封界面的分形参数、泄漏通道的流动阻力以及密封界面的有限尺寸效应对泄漏特性的影响,指出孔隙连通贯穿界面和流体流经贯穿通道的流动阻力小是密封界面产生泄漏的成因,以及泄漏通道的形成和泄漏通道内的流体流动特性是泄漏机理研究的主要方向。     

Measured kinetics of the acid-catalysed hydrolysis of sugar cane bagasse to produce xylose

Experimental trials of the water hydrolysis of bagasse to produce xylose, arabinose and glucose were conducted using a temperature-controlled microwave digester. The experimental variables were temperature, ratio of water mass to bagasse mass, type of bagasse material and reaction time. The pH of the liquid and concentration of dissolved xylose, arabinose and glucose were measured at the completion of each trial. Kinetic modelling of the global rates of formation of monosaccharide products was performed using schemes based on earlier researchers’ models of acid hydrolysis using mineral acids. For the most plentiful product, xylose, the most accurate kinetic model of the global reactions was determined to be two parallel pathways for hydrolysis of xylan to xylose followed by a single pathway for xylose decomposition. The calculated activation energies of the reactions were within the range reported by other researchers for the hydrolysis of a range of lignocellulosic materials using mineral acids.     

Biogenic and bio‐structured inorganic materials in heterogeneous catalysis: a brief overview

This mini‐review highlights some research results related to the production and application of biogenic and biomorphic materials in catalysis. Such approaches are of interest for the preparation of materials of unusual and well defined morphology, as well as the recovery of valuable resources from waste streams. Areas covered are the application of biogenic iron oxide occurring as a natural waste in the form of iron ochre which can cause issues in water management, the application of biogenic manganese oxide materials formed from manganese rich media (and therefore possibly playing a role in water remediation), the application of bacteria for the preparation of metal nanoparticles of potential relevance to precious metal recovery from waste streams and the application of natural biological materials as templates for biomorphic inorganic materials of controlled and unusual uniform morphology. © 2015 Society of Chemical Industry