固载AlCl_3催化甲基三氯硅烷/三甲基氯硅烷再分配反应实验研究

针对有机硅单体二甲基二氯硅烷生产中的副产物—甲基三氯硅烷(—甲)和三甲基氯硅烷(三甲),采用固载 AlCl_3催化剂,在800mm×20mm(内径)的固定床反应器中进行一甲和三甲的再分配反应,制得二甲基二氯硅烷。通过催化剂筛选试验,结果表明以活性炭为载体的固载 AlCl_3催化剂为佳。通过工艺条件实验,确定了在活性炭固载 AlCl_3催化剂上一甲和三甲再分配反应的适宜工艺条件为:反应物摩尔比为1.0.液时空速 LHSV 为0.66 mL/(h·g-cat),反应温度为320℃,得到二甲收率70%左右。该催化剂还表现出一定的催化稳定性。     

铀水冶密实固定床离子交换塔新型反冲出水装置的研制

通过对现有铀水冶密实固定床离子交换塔的反冲出水装置所存在的问题进行分析,提出一种新型反冲出水装置,可有效降低塔内和反冲出水装置所承受压力,达到减少装置泄漏和树脂破损率的目的.     

O2/H2O燃烧方式下石灰石的间接硫化反应特性

利用水平管式炉和热重实验台架,对O₂/H₂O、O₂/N₂和O₂/CO₂ 3种不同燃烧方式下石灰石的间接硫化反应特性进行了研究。重点探究了燃烧方式、水蒸气浓度对石灰石间接硫化反应的影响规律与机理。同时,对硫化产物进行了X射线荧光光谱（XRF）、X射线衍射（XRD）、孔结构特性和扫描电镜（SEM）分析。结果表明,O₂/H₂O燃烧方式相比于相同氧浓度下的O₂/N₂和O₂/CO₂燃烧方式,石灰石间接硫化反应的钙转化率在化学反应控制阶段基本相同,在扩散控制阶段O₂/H₂O燃烧方式下的钙转化率有显著的提高。主要原因是水蒸气促进了硫化反应后期产物层内的固态离子扩散。此外,O₂/H₂O燃烧方式下,不同的水蒸气浓度对石灰石的钙转化率基本没有影响。     

Kinetics and reaction mechanism of catalytic oxidation of low concentrations of hydrogen sulfide in natural gas over activated carbon

The kinetics of the hydrogen sulfide oxidation process, producing mostly sulfur and water, was studied using 0.25 to 1.0 g Hydrodarco activated carbon catalyst and varying the O₂/H₂S ratio (molar basis) in the feed gas between 0.5 to 0.6 in the temperature, and pressure ranges from 125 to 200°C and 225 to 780 kPa. SO₂ was obtained as an undesirable by-product during H₂S oxidation reaction or as a product during regeneration of the catalyst. The feed gas contained 0.9 — 1.3 mol% H₂S with approximately 80 mol% CH_4. In this paper, the factors affecting the H₂S conversion and SO₂ formation are presented. The rate expressions for (a) H₂S conversion and (b) SO₂ formation were developed from the Langmuir-Hinshelwood surface control reaction model. The experimental data were well correlated by the rate equations. Also, the rate parameters were evaluated and correlated with temperature. The activation energies for H₂S oxidation and SO₂ production reactions were calculated to be 34.2 and 62.5 kJ/mol, respectively. Partial pressures of oxygen and H₂S were found to influence H₂S conversion whereas, the presence of water in the feed gas up to 10.5 mol% did not affect H₂S conversion significantly. Heats of adsorption for various species on the active sites were calculated. SO₂ production was, as expected, enhanced at higher temperature, and its rate was much smaller than the oxidation rate of H₂S under the reaction conditions used.     

Reactivity stabilization and capacity study of fabricated alumina and zirconia-supported CaO-based sorbents for high-temperature CO2 capture in a fixed-bed reactor

Calcium looping process is a promising approach for CO₂ capture from the flue gas of fossil fuel power plants and the cement industry. Even though the advantages of calcium-based sorbents are low cost and high uptake capacity, they suffer from low durability during cycles. Modified sorbents were fabricated by adding alumina and zirconia and the mixture of alumina and zirconia to calcium oxide via the co-precipitation method. The performance of synthesized sorbents in terms of stability and CO₂ capture capacity were evaluated using a fixed bed reactor in various CO₂ sorption/desorption cycles. The sorbents were fabricated by a co-precipitation methodology using 10% binders (alumina and/or silica). X-ray diffraction (XRD), BET/BJH, and scanning electron microscopy (SEM) were conducted for characterization of synthesized sorbents. CaO-10% ZrO₂ showed the best performance among the fabricated sorbents in terms of stability during 5 cycles and CO₂ capacity (14 mmol CO₂/g sorbent). The formation of CaZrO₃ with a perovskite structure and high-temperature resistance could be attributed to well performance of zirconia-supported sorbent. On the other hand, no sign of aluminum zirconate formation was approved in XRD analysis for the fabricated sorbent using mixed binders of zirconia and alumina to enhance its stability during cycles.     

不同温度区间内污泥热解气固相产物特征

对城市污水污泥（简称污泥）进行工业分析和热重分析,考察污泥的基本组成和热重特性;采用气相色谱（GC）检测了不同热解温度区间内污泥热解生成的气体产物成分,并利用SEM和BET分别分析了不同热解终温下裂解炭的形貌特征和比表面积。结果表明：污泥热解可以分为水分析出阶段、挥发分析出阶段和焦炭化阶段;不同热解温度区间内污泥热解气体产物的组成有很大差别,热解温度350℃后H₂在热解气中的含量快速增加,CH₄含量在350～450℃时达到最大值,而CO主要在热解温度为350～750℃时生成,CO₂含量随着热解温度的增加迅速下降;随着热解终温的不断升高,裂解炭结构变得越来越疏松,比表面积也随之增大,750℃达到最大值55 m²·g^-1。     

烯烃催化裂解反应器局部颗粒堆积结构的颗粒解析模拟

烯烃催化裂解固定床工艺中的反应过程对压力敏感,深入研究催化剂堆积颗粒结构中的流动及压力分布对优化固定床结构及操作参数有重要意义。颗粒解析模拟方法广泛用于固定床内堆积结构的模拟,可以准确描述堆积结构中的流体力学行为,但对于复杂堆积结构网格生成困难。采用基于多孔介质模型的浸入边界法(PMM-IBM)结合网格自适应,实现了对固定床堆积结构的颗粒解析模拟,既解决了网格划分困难的问题,又节省了计算资源。采用网格自适应技术后,与均匀网格相比,堆积结构的网格总数减少大约80%。通过与贴体网格法的单颗粒表面受力分析对比,确定了此浸入边界法的关键模拟参数。随后模拟预测了三种床层与颗粒直径比值条件下堆积结构的空隙率及其内部的压力及流动分布。研究表明,堆积结构空隙中的局部轴向速度的最大值可以达到入口速度的10倍以上,轴向平均速度的径向分布与轴向平均空隙率分布一致,均成震荡衰减趋势。除此之外,预测的床层压降与Reichelt经验关联式结果较为吻合。在此基础上,耦合单颗粒内扩散和烯烃裂解的主反应,预测了反应物随孔径和孔隙率的变化,为进一步考虑外流场的变化奠定了方法基础。     

垃圾焚烧电厂飞灰在固定床中烧结的数值模拟

针对某垃圾焚烧飞灰固定床烧结无害化处理炉,建立了炉内流动、传热传质和燃烧的数值模型．利用Fluent软件对设计工况下的烧结炉进行数值模拟,采用多孔介质模型来计算炉内气体流动和压强分布,采用缩核模型来描述炉内物料的燃烧反应过程,得到了炉内气流速度场、温度场、气体组分分布以及烧结物料的温度分布．结果表明：鼓风进入风口0．2m后,速度变化平缓且分布较为均匀;物料的燃烧反应主要发生在风口中心线以上0．3～0．55m的区域内,物料下行至风口中心截面时已经燃烧完全;当掺煤量为12％、物料直径为16mm、过量空气系数为1．2时,炉内物料的温度为1138～1400K,完全可以满足无害化烧结工艺的要求．     

高温下改性钙基吸附剂固定床反应器从烟气中捕捉二氧化碳(英文)

Four kinds of Ca-based sorbents were prepared by calcination and hydration reactions using different precursors: calcium hydroxide, calcium carbonate, calcium acetate monohydrate and calcium oxide. The CO2 absorption capacity of those sorbents was investigated in a fixed-bed reactor in the temperature range of 350-650℃. It was found that all of those sorbents showed higher capacity for CO2 absorption when the operating temperature higher than 450℃. The CaAc2-CaO sorbent showed the highest CO2 absorption capacity of 299mg·g-1. The morphology of those sorbents was examined by scanning electron microscope (SEM), and the changes of composition before and after carbonation were also determined by X-ray diffraction (XRD). Results indicated that those sorbents have the similar chemical compositions and crystalline phases before carbonation reaction [mainly Ca(OH)2], and CaCO3 is the main component after carbonation reaction. The SEM morphology shows clearly that the sorbent pores were filled with reaction products after carbonation reaction, and became much denser than before. The N2 adsorption-desorption isotherms indicated that the CaAc2-CaO and CaCO3-CaO sorbents have higher specific surface area, larger pore volume and appropriate pore size distribution than that of CaO-CaO and Ca(OH)2-CaO.     

催化剂结构与焦油模型化合物裂解行为的关联性

以Ni（NO₃）₂·6H₂O为镍源,分别以HZSM-5（Si/Al=25）、HZSM-5（Si/Al=50）、HZSM-5（Si/Al=200）、USY、Al₂O₃为载体制备了5种镍基催化剂,采用XRD、H₂-TPR、BET、NH₃-TPD等方法对其进行了表征,在固定床反应器中考察了上述催化剂对煤焦油模型化合物甲苯+芘的催化裂解性能。结果表明,相比惰性载体石英砂,在催化剂作用下,液相产物中轻质芳烃种类明显增多。3种Ni/HZSM-5催化剂的比表面积和平均孔径较为接近,然而酸性中心数量最多的Ni/HZSM-5（Si/Al=25）,对甲苯+芘的裂解能力最强,体现为液体产物收率最低（仅为15.95%）,气产率和析碳率均最高,分别达16.73%和67.32%。在酸性中心数量相近的Ni/HZSM-5（Si/Al=200）与Ni/Al₂O₃作用下,液体产物收率差别较小,但后者的芘裂解率比前者高41.47%,主要是由于后者的平均孔径比前者高1.64倍,说明平均孔径大有利于重质组分芘的裂解。综合考虑液体产物收率、气产率、析碳率和芘的裂解率,Ni/Al₂O₃更适合甲苯+芘裂解反应体系。