Enhanced performance of Ca-doped Pt/γ-Al2O3 catalyst for cyclohexane dehydrogenation

The promotion effects of Ca on catalytic performance of Ca-doped Pt/Al₂O₃ catalyst were investigated by varying Ca content and impregnation orders. The Ca-doped Pt/Al₂O₃ catalyst with atomic rate Ca/Pt = 5 exhibited the highest catalytic activity and stability. Detailed analyses show that low Ca content (Ca/Pt ＜ 5) could not efficiently promote hydrogen spillover from Pt-Al interface to the support and reduce the strong acid sites on the support. However, high Ca content (Ca/Pt > 5) decreases the initial activity due to the coverage of Ca on the support and increases the amount of Pt strongly interacting with Ca, which inhibits Pt reduction. Furthermore, the Ca promotion effect is more pronounced when Ca is added prior to Pt due to surface modification of Ca on Al₂O₃ support. This modified catalyst possesses more dispersed Pt, lower acidity and larger amount of spilled-over hydrogen.     

Case study and theoretical analysis of a solar driven two-stage rotary desiccant cooling system assisted by vapor compression air-conditioning

In this paper, a solar hybrid desiccant air conditioning system, which combines the technologies of two-stage desiccant cooling (TSDC) and air-source vapor compression air-conditioning (VAC) together, has been configured, experimentally investigated and theoretically analyzed. The system mainly includes a TSDC unit with design cooling capacity for 10 kW, an air-source VAC unit with 20 kW in nominal cooling capacity, a flat plate solar collector array for 90 m², a hot water storage tank and a cooling tower. Performance model of the system has been created in TRNSYS simulation studio. The objective of this paper is to report the test result of the solar hybrid air conditioning system and evaluate the energy saving potential, thereby providing useful data for practical application. Experimental results show that, under typical weather condition, the solar driven desiccant cooling unit can achieve an average cooling capacity of 10.9 kW, which contributes 35.7% of the cooling capacity provided by the hybrid system. Corresponding average thermal COP is over 1.0, electric COP is up to 11.48. Under Beijing (temperate), Shanghai (humid) and Hong Kong (extreme humid) weather conditions, the solar TSDC unit can remove about 57%, 69% and 55% of the seasonal moisture load, thereby reducing electric power consumption by about 31%, 34% and 22%, respectively. These suggest that the solar hybrid system is feasible for a wide range of operating conditions.     

评定焊接材料的晶间腐蚀敏感性应注意的问题

本文通过对几个原材料母材和焊接试样的对比试验,结合国家标准中关于焊接材料试样尺寸的规定,进行计算与理论分析,得知焊接材料在晶间腐蚀敏感性试验中不适合进行弯曲评定的特性,并且依据国家标准中相关说明,重点指出了晶间腐蚀敏感性试验应该注意的问题,为试样的选择、制备及相关检测过程提出了合理化建议.     

SZS35-1.4-QD燃电石炉尾气锅炉的设计开发

针对电石炉尾气的成分特性,以一台35 t/h锅炉为例,从降低排尘及减少可燃性气体排放的角度详细介绍燃电石炉尾气锅炉设计开发过程,从而解决电石炉尾气污染问题.     

类胡萝卜素发酵生产条件的研究

对影响红假单胞菌产类胡萝卜素的因素作了较全面的研究,获得了类胡萝卜素产量较高的培养条件：以乙酸钠为碳源,谷氨酸钠为氮源,酵母膏为生长因子,4mg／LMgSO4,2mg／LFe2（SO4）3,15001X光照度,30℃,微好氧培养120h。在此条件下R-41菌株的类胡萝卜素产量由23．8mg／g干菌体提高到57．3mg／g干菌体。     

平面砂带磨床磨削参数的优化设计

砂带磨削是一种高效的磨削技术。通过优化设计方法对砂带磨削过程进行分析,建立了平面砂带磨床工艺参数的数学模型,采用内点罚函数法对其优化求解,获得了最优磨削参数。将最优参数和传统经验值进行比较,结果表明了最优参数的可行性。     

沉淀法制备苯选择加氢制环己烯Ru-Zn催化剂的表征

沉淀法制备的Ru-Zn体系用于苯选择加氢制环己烯,苯转化40%时,环己烯选择性达85 5%。XRD研究证实了Zn和Ru以固溶体形式存在。用噻吩吸附发现,10-6数量级的硫对选择性产生明显影响。XRD半高宽法测得Ru微晶粒径3～5nm。Ru-Zn催化剂BET比表面积62 5m2/g,平均孔径16 05nm,具有两端开放的管状毛细孔结构,反应可利用的孔分布均匀。并与浸渍法制备的Ru-Zn/SiO2对比,探讨催化剂的活性相,活性中心性质,及比表面积、孔性质与活性选择性的关系。     

电潜泵中压变频调速系统的改进

电潜泵中压变频器输出端产生高次谐波和脉冲电流 ,对电潜泵电动机的绝缘性能和轴承寿命造成不利影响。为此 ,提出 3项改进对策 :①采用谐振软性开关逆变电路 ,使功率开关器件在零电压条件下导通 ;②在变频器逆变输出端设置电抗滤波器抑制高次谐波电流 ;③改变电动机内部结构 ,如加大定子槽宽 ,增加转子导条尺寸 ,变星接法为星 角接法 ,采用绝缘轴承等。实践证明 ,采取改进对策后 ,不仅提高了电潜泵的产量 ,而且变频器滤波后电动机端的过电压明显减小 ,电潜泵和电缆的寿命延长     

松辽盆地西部扶杨油层成藏条件和勘探潜力

大庆长垣以西地区扶杨油层是后备储量接替的重要勘探目标之一。油层的成藏机理、成藏过程及油气分布规律 ,特别是 2 0 0 0m以下储层的勘探潜力的认识制约油气勘探 ,扶杨油层具有形成顶生下储式岩性油藏的成藏条件。青一段烃源岩在运移期油气垂向下排深度近百米 ,从齐家 古龙凹陷向两侧隆起油柱高度增大 (最大 2 75 0m) ,扶杨油层经历了多期大规模的侧向运移 ,依安组末期的构造运动是扶杨油层成藏的关键地质时期 ,古构造、断裂、储层物性是西部扶杨油层成藏的主要控制因素。指出了环齐家 古龙凹陷周边地区是扶杨油层勘探的有利区 ,并优选 7个目标 ,估算石油资源量3 6× 10 8t。     

催化氧化法合成脂肪醇醚羧酸盐的研究进展

详细介绍了氮氧自由基催化氧化法和贵金属催化氧化法合成脂肪醇醚羧酸盐。氮氧自由基催化时,反应温度20～60℃,反应时间3～6 h,得到酸型产品。贵金属催化剂中,钯的催化活性比铂高。贵金属催化时,加入铅、铋等助催化剂,并以活性炭为载体,碱性条件下于50～90℃反应2～6 h,得到盐型产品。在适当的条件下,这两种方法均可使醇醚转化率达95％,选择性达90％以上。