C302铜基甲醇合成催化剂颗粒设计Ⅱ. 颗粒结构对Lurgi型合成反应器性能的影响

基于本文（I）报的研究结果，以固定床反应器二维非均相数学模型为基础，模拟考察了C302铜基甲醇合成催化剂颗粒设计对Lurgi型合成反应器性能的影响。结果表明，由于颗粒结构设计改变了粒内反应－扩散耦合行为的相互匹配关系，使得催化剂的宏观反应活性发生变化，进而对反应器的操作性能产生显著的影响（包括反应器生产能力、温度和浓度分布特性、床层压力降和热点温度等），为提高反应器的生产能力和改善反应器的操作性能，进行催化剂颗粒的适宜结构设计是非常必要和有价值的。     

在透氧膜反应器中进行甲烷氧化偶联反应的研究

 混合导体透氧膜是一类同时具有电子和氧离子两类导电性的陶瓷膜．在高温下，氧会以氧离子的形式透过透氧膜，因此在膜表面存在丰富的氧物种（O－，O－2，O2－2和O2－），这些氧物种能够提高甲烷氧化偶联（OCM）反应的C2选择性．采用挤压的方法制备出致密的Ba0．5Sr0．5Co0．8Fe0．2O3－δ（BSCFO）透氧膜管，并考察了此透氧膜管对OCM反应的催化性能．发现BSCFO的C2生成速率比La0．6Sr0．4Co0．8Fe0．2O3－δ（LSCFO）和La－Ba－Co－Fe－O（LBCFO）要高得多，其原因主要是由于BSCFO中的氧空缺浓度比较高．高的氧空缺浓度不仅能够加速氧离子的传输，而且能够提高甲烷分子的活化速度，所以BSCFO具有比LSCFO和LBCFO更好的催化性能．C2生成速率随着反应温度及原料气中甲烷浓度的升高而升高，C2选择性取决于氧离子结合与OCM反应竞争的结果，高的氧离子结合速率会降低C2选择性．甲烷转化率随着富氧侧氧分压的升高而升高，但C2选择性则随着氧分压的升高而降低．这说\r\n明在OCM过程中气相反应起着重要的作用．     

无机膜反应器中乙苯脱氢反应的研究

无机膜反应器中乙苯脱氢反应的研究钟丽，杨维慎，刘杰，丛铀，刘世河，林励吾（中国科学院大连化学物理研究所，大连１１６０２３）关键词膜反应器，乙苯，脱氢，微孔氧化铝膜将耐高温、耐腐蚀、结构较稳定的无机膜应用于高温催化反应，使反应与分离联为一体，已成为近年...     

NiO@SiO_2核壳催化剂在浆态床中低温甲烷化研究

采用改进的Stber方法,可控制备出具有不同形貌的NiO@SiO_2核壳结构催化剂,并在浆态床反应器(320℃)上,对其合成气低温甲烷化性能进行评价;同时借助XRD、TEM、XPS和N_2物理吸附等方法对反应前后催化剂的物化性质进行了表征。研究表明,实验制备的催化剂形貌规整、粒径均匀,且具有较好的热稳定性。在相同的制备条件下,核颗粒粒径增大,其SiO_2壳层的厚度随之增加。在反应过程中,部分催化剂的核壳结构遭到破坏并出现SiO_2空壳,是CO与壳层内的Ni作用生成易迁移的Ni羰基化物种(Ni(CO)_x)所致。催化剂的甲烷化活性随着核颗粒粒径的增加呈现下降趋势;在不同的反应阶段,催化剂的失活速率存在明显差异,在反应的前20 h内,催化剂出现快速失活,20 h后失活缓慢,但是催化剂的甲烷选择性都保持在80%左右。催化剂的失活,一方面,是因为反应过程中,Ni核颗粒发生了长大;另一方面,是由于壳层中3-5 nm的介孔的减少以及催化剂比表面积、孔容的下降。     

煤-焦炉气共热解特性的研究Ⅰ.固定床热解反应特性

在１０ｇ固定床反应器中对先锋褐煤在焦炉气气氛下的热解特性及有关工艺参数，如反应压力、升温速率等的影响进行了详细考察，并与其同等条件下的加氢热解特性进行了对比分析。实验结果表明，在反应压力５ＭＰａ、升温速率５Ｋ／ｍｉｎ，终态温度９２３Ｋ条件下，先锋褐煤在焦炉气气氛下的热解转化率为５９．０％（ｄａｆ），焦油收率达３５．８％（ｄａｆ）。与同等条件下的纯氢气氛（３ＭＰａ）相比，转化率降低了约７％（ｄａｆ），而焦油收率提高了约７％（ｄａｆ）。这说明焦炉气中的诸如甲烷等其它组分的存在对煤的热解行为有重要作用。由于煤加氢热解受传质影响，因此不同工艺参数对热解反应影响很大，较高压力下的慢速升温有利于提高转化率和油品收率；升温速率对油品收率影响较为明显，慢速升温有利于提高油品收率。     

Solid-phase reactor flow-injection on-line oxidizing spectrofluorimetry for determination and dissolution studies of folic acid

A simple, sensitive and specific flow-injection spectrofluorimetric method has been developed for the determination of folic acid in pharmaceuticals. The method is based on use of a lead dioxide solid-phase reactor for on-line oxidation of folic acid into a strongly fluorescent compound with a maximum excitation wavelength of 281 nm and an emission wavelength of 450 nm. Under optimum conditions the fluorescence intensity of oxidation product is proportional to the concentration of folic acid over the range 0.008–2.5 g mL^–1. The detection limit is 0.0001 g mL^–1, the relative standard deviation is 0.85% for 11 replicate determinations of 0.05 g mL^–1 folic acid, and the sample throughput is 20 h^–1. In combination with an on-line filter and dilution, an automated drug-dissolution system was established. The proposed method has been successfully applied to the determination of folic acid in pharmaceutical preparations and dissolution testing.     

甲醇气相缩合制二甲醚反应动力学研究

在管式活塞流反应器上进行了甲醇在HZSM-5上缩合制二甲醚反应稳态动力学研究,获得了该反应是由双吸附甲醇分子或吸附甲醇分子与气相甲醇分子进行表面反应为控制步骤的动力学模型及其参数。     

Oxidative Coupling of Methane over Na-W-Mn/SiO2 Catalysts at Elevated Pressures

Na-Mn-W/SiO2 catalysts were studied for the oxidative coupling of methane (OCM) in a micro fixed bed reactor made of stainless steel reactor at elevated pressures. The effect of operating conditions, such as GHSV, pressure, temperature and CH4/O2 ratio on the catalytic performance of OCM was investigated. The C2+ selectivity of 80.3% was obtained at a CH4 conversion of 16.1% at 750℃,1.5× 105h-1 GHSV, and 0.6 MPa. Also, there is a small output of C3 and C4 hydrocarbons in the tail gas. The results show that unfavorable effects due to elevated pressure can be overcome by increasing GHSV, and the OCM reaction is strongly dependent on the operating conditions at elevated pressures,particularly GHSV and the CH4/O2 ratio.     

Bulk determination of uranium and thorium in presence of each other by Total Reflection X-ray Fluorescence spectrometry

A study to assess the applicability of Total Reflection X-ray Fluorescence (TXRF) spectrometry as a microanalytical technique for the determination of uranium and thorium as major elements in presence of each other has been made. Effect of dilution of the sample on the analytical results has been investigated. It has been found that dilution of the sample does not affect the analytical results significantly. Also the analytical results of uranium and thorium are similar with different internal standards e.g. cobalt, gallium and yttrium. With a sample size of 10 μL and the concentrations of the analytes in the range of 1–50 μg/mL and total matrix concentration less than 200 μg/mL, the precision and accuracy of the method were found to be better than 3% (1 s) and 4%, respectively. For higher concentration ranges of the analyte (up to about 700 μg/mL), the precision and accuracy values were better than 6% (1 s) and 5%, respectively. The TXRF method has an advantage of using small sample volume of about 10 μL, produces very small radioactive waste and is nondestructive but requires dissolution of the sample.     

The preparation and reaction of enolates within micro reactors

Over the past 5 years, interest in the miniaturisation of chemical synthesis has grown rapidly, however in order to facilitate transfer of the technology from its current position as a research tool to industrial applications, a core understanding of the challenges associated with transferring reactions from the macro to the micro domain is required. This paper therefore aims to broach this problem by investigating the application of micro reactors to a range of commonly employed synthetic reactions including acylation, aldol, alkylation, 1,4-conjugate addition (Michael addition) and the Knoevenagel condensation. Comparison of the results obtained with traditional batch techniques enable us to highlight some of the advantages associated with micro reaction technology.