轴向固定床反应器内压降的数值模拟与分析

固定床反应器的压降变化对化学反应效果影响较大,而以实验为主的研究方法无法实时和形象地表达固定床内压降的变化规律.在CSP概念的基础上,以不同管径比为参数建立了轴向固定床反应器的物理模型;利用计算流体动力学软件FLUENT对空隙率ψ=0.48、0.63和0.69等3种不同的催化剂排布方式进行了数值模拟,结果表明,ψ=0.48时反应器内压降最大,而ψ=0.63、0.69时反应器内出现多个回流区域,其耦合结果使整个反应器内的压降在ψ=0.69时最小.分析认为,对于不同类型的化学反应,应采用不同的催化剂排布方式才能达到最佳的反应效果.     

Preparation and characterization of Ce_1-xNi_xO₂ as oxygen carrier for selective oxidation methane to syngas in absence of gaseous oxygen

A citric acid complex method was employed to prepare Ce/Ni mixed oxides with various Ce/Ni ratios useful for selective oxidation methane to syngas in the absence of gaseous oxygen,and the catalytic activity measurement was investigated in a fixed bed reactor at 800 oC.The prepared oxygen carriers were characterized by various characterization techniques such as TG-DSC,XRD and TPR.The results of TG-DSC indicated that the Ce1-xNixO2 precursor generated a stable phase after the heat-treatment at temperatures above 800 oC.The XRD characterization suggested that some Ce-Ni solid solution was formed when Ni2+ ions was incorporated into the lattice of CeO2,and it led to the generation of O-vacancy which could improve the oxygen mobility in the lattice of oxygen carriers.It was found that Ce0.8Ni0.2O2 gave the highest activity in the selective oxidation methane to syngas reaction,and the average methane conversion,CO and H2 selectivity reached to 82.31%,82.41% and 87.64%,respectively.The reason could be not only attributed to the fitting amount of NiO dispersed on the CeO2 surface and bulk but also to actual lattice oxygen amount increased in oxygen carrier.     

Al@AlN-Al2O3高温复合相变蓄热材料的制备与性能研究

以Al作为相变材料,采用直接氮化法制备出一种核壳结构Al@Al N-Al_2O_3新型高温复合相变蓄热材料。利用X射线粉末衍射仪、扫描电子显微镜、能谱仪、拉曼光谱仪和差示扫描量热分析仪对材料进行表征。进一步研究锂盐助剂种类及反应时间对材料合成的影响,同时对材料的热循环性能进行测定。结果表明:在750℃条件下制备的复合材料达到预期的核壳结构,其相变材料含量64.6%,相变温度为662.3℃,蓄热密度高达326.3 kJ/kg。同时发现Li_2CO_3助剂的加入、反应时间的延长均可促进AlN的合成,从而使核壳结构更加稳定。经过20次热循环后,该材料仍表现出稳定的蓄热性能。     

利用钢铁企业煤气制备化工产品的研究

提出了以钢铁企业富含碳资源的高炉煤气、转炉煤气和富含氢资源的焦炉煤气制备化工产品的技术路线。以高炉煤气制备甲醇的资源化路线为例,构建了煤气资源化利用的环境—经济评价模型,并就普通高炉煤气和全氧高炉煤气资源化利用的减排效果和经济性进行了评价和分析。高效的资源化利用,不仅可实现CO2减排,还可廉价地获得高附加值化工产品。采用全氧高炉煤气制备甲醇,CO2减排效果更为明显。     

Catalytic performance of cerium iron complex oxides for partial oxidation of methane to synthesis gas

The cerium iron complex oxides oxygen carrier was prepared by the co-precipitation method. The reactions between methane and lattice oxygen from the complex oxides were investigated in a fixed micro-reactor system. The reduced oxygen carder could be re-oxidized by air and its initial state could be restored. The characterizations of the oxygen carders were studied using XRD, O2-TPD, and H2-TPR. The results showed that the bulk lattice oxygen of CeO2-Fe2O3 was found to be suitable for the partial oxidation of methane to synthesis gas. There were two kinds of oxygen species on the oxygen carrier： the stronger oxygen species that was responsible for the complete oxidation of methane, and the weaker oxygen species （bulk lattice oxygen） that was responsible for the selective oxidation of methane to CO and H2 at a higher temperature. Then, the lost bulk lattice oxygen could be selectively supplemented by air re-oxidation at an appropriate reaction condition. CeFeO3 appeared on the oxygen carrier after 10 successive redox cycles, however, it was not bad for the selectivity of CO and H2.     

铜基载氧体的焦炉煤气化学链燃烧特性

焦炉煤气(COG)是炼焦过程产生的主要副产品,含有复杂的气体成分(CO、H₂、CH₄、CO₂),化学链燃烧是一种可实现COG高效转化与高纯CO₂捕集的技术。通过溶胶凝胶法制备了一系列x(%)CuO/Ce-Zr-O(x=30、50、70、90)载氧体用于COG化学链燃烧反应特性研究。XRD表明,x(%)CuO/Ce-Zr-O载氧体物相由CuO和Ce_0.67Zr_0.33O₂固溶体组成。由于Zr⁴⁺进入CeO₂晶格中,在617 cm^-1处出现明显的氧空位Raman特征峰。H₂-TPR、CO-TPR、CH₄-TPR和COG-TPR结果表明加入Ce-Zr-O固溶体促使铜物种低温释氧能力增强。800℃下,CuO样品CO₂捕集率为34%,添加10%Ce_0.67Zr_0.33O<...     

选择性硫化法有效分离高砷锑烟尘中的砷和锑（英文）

以硫磺为添加剂对高砷锑烟尘进行硫化焙烧,可实现物料中砷、锑的高效分离。借助XRD、EPMA和SEM-EDS等表征手段,对焙烧温度、焙烧时间、硫磺添加量和氮气流量对物料中砷、锑分离效率的影响进行研究。结果表明,在一定添加范围内,硫磺对高砷锑烟尘中砷的挥发脱除具有显著促进作用,原因是硫磺可将高砷锑烟尘中固熔体(Sb,As)_2O_3结构中的Sb组元硫化转变为Sb_2S_3,使As_2O_3组分得以解离释放,促进砷挥发率的提高;同时,高砷锑烟尘中Sb_2O_3物相可硫化生成Sb_2S_3,对As_2O_3和Sb_2O_3之间的非晶反应形成阻碍,亦有利于砷的挥发。在焙烧温度350°C、焙烧时间90 min、硫磺添加量22%和N_2流量70 m L/min的试验条件下,砷挥发率可达95.36%,锑挥发损失率仅9.07%,实现砷锑烟尘中砷、锑的高效分离。