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。     

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.     

EDTA辅助制备高活性费托合成催化剂

费托合成（FTS）对天然气、煤炭和生物质向清洁运输燃料和增值化学品的转化至关重要。传统上,用于FTS的负载型铁催化剂主要是以氧化铝和二氧化硅为载体。然而,金属与载体的相互作用阻碍了活性相碳化铁的形成,使得催化剂活性较低。本文通过乙二胺四乙酸（EDTA）络合浸渍制备了Fe/Al₂O₃催化剂,通过带正电荷的羟基（OH{}_{\mathrm{2}}^{+}）与[Fe(EDTA)]^-配合物阴离子之间的库仑相互作用来提高氧化铝载体上铁物种的分散度。采用X射线衍射（XRD）、扫描电子显微镜（SEM）、透射电子显微镜（TEM）、X射线光电子能谱（XPS）、比表面积（BET）、原位红外（In-situ IR）等手段进行表征分析。结果表明,添加EDTA有助于增强Fe的抗烧结性。在煅烧络合浸渍制备样品的过程中,EDTA可以分解为具有还原性质的有机小分子,将催化剂中的铁物种还原为Fe²⁺,有利于催化剂的还原;更多活性中心增强了催化剂对CO的吸附量。原位红外实验表明,EDTA辅助制备的催化剂更容易富集活性物种,从而提高CO的转化率。调节体系中碱金属钠的含量改善了烃内产物分布。在较低的氢碳比（H₂/CO=1/1）下,EDTA络合制备的Fe-Na/Al₂O₃催化剂显示出高的CO转化率（88.5%）以及最大的C₂~C₄=和C₅~C₁₁选择性,总选择性达71.2%。     

轻烃催化裂解制低碳烯烃反应规律与原料特征化

利用小型固定床实验装置对比研究了轻烃模型化合物的催化裂解性能,从优到劣的顺序依次是正构烯烃、正构烷烃、环烷烃、异构烷烃、芳香烃。正构烷烃、异构烷烃与环烷烃催化裂解的总低碳烯烃收率有较大差别,但是总低碳烯烃选择性却均在56.57%左右。研究了直馏石脑油的催化裂解性能,发现乙丙烯收率和总低碳烯烃收率随反应温度的升高及重时空速的降低而逐渐增大;在反应温度680℃、重时空速4.32 h^-1和水油稀释比0.35的条件下,乙丙烯收率35.87%（质量）,总低碳烯烃收率为41.94%（质量）。针对轻烃催化裂解提出了原料特征化参数KF,它是原料H/C原子比、相对密度与分子量的函数,能较好地表征轻烃原料的催化裂解性能。     

Trace element behaviour in the Sasol-Lurgi MK IV FBDB gasifier. Part 2 - The semi-volatile elements: Cu, Mo, Ni and Zn

Gasification is a coal conversion process that could be considered to be more amenable with regards to environmental impact factors when compared to combustion, as it provides minimum direct emission to the atmosphere due to the opportunity to apply a series of gas cleaning processes. Emissions could be in the form of the well known trace elements labelled as toxic present in feed coal. Due to the minimal literature available on coal gasification when compared to coal combustion, a large amount of inference to coal combustion has been applied in discussing the partitioning behaviour of trace elements during coal utilization. Conducting mass balance calculations of trace elements around gasification processes have proven to be a challenging task. This is due to the limitation of the analytical techniques employed to quantify at the parts per million levels at which trace elements exist. The other challenge is analyzing for trace elements in all the different stream phases that occur after gasification. The availability of thermodynamic equilibrium packages i.e. Fact-Sage to perform high temperature calculations, at the same time handling all phases of material involved has simplified the challenges. Results obtained from such calculations have also proved to be close to reality, but have not been related to the fixed-bed counter-current gasification reactor operating on lump coal.The focus of this paper is to discuss more recent environmentally-focused research developments by Sasol, where trace element simulation and validation of model predictions have been undertaken for the gasification process. Fact-Sage thermodynamic equilibrium modelling was used to simulate the semi-volatile trace elements (Cu, Mo, Ni and Zn) gas phase and ash phase partitioning and speciation behaviour occurring in a fixed-bed pressurized gasifier. A Sasol-Lurgi Mark IV FBDB gasifier was mined via turn-out sampling in order to determine the trace element changes through the gasifier, results being used to validate the modelled results.The semi-volatile elements: Cu, Mo, Ni and Zn all showed limited (5% in the case of Zn) de-volatilization behaviour in the drying and pyrolysis zone of the fixed-bed gasifier. Predictions revealed that within the reduction zone of the fixed-bed gasifier that they are all highly volatile, producing gaseous species with an increase in temperature, varying in the order: Zn > Mo > Cu > Ni, which is contrary to what was found from the experimental results. This could imply that thermodynamic equilibrium conditions do not necessarily prevail in a fixed-bed gasifier operating on lump coal, since in reality mass and heat transfer limitations across coarse coal particles apply and the reactions are therefore more kinetically limited. Over-balances of Ni and Mo partitioning to the solid ash fraction, was found for the measured results. This anomaly was found to not be caused by erosion of the gasifier internals, but rather possibly be ascribed to accumulation and contamination caused by likely condensation and vaporisation of these species during the gasifier sampling campaign, as well as by the particle size reduction processes utilized prior to elemental analyses. Leaching tests conducted on the bottom ash collected from the gasifier have shown that the trace elements studied are firmly bound into the ash matrix and therefore would not be released during later disposal. The relative enrichment in trace element content observed for Ni and Mo within the gasifier should be further investigated.     

Synthesis, characterization and performance of CuO/La2O3 composite catalyst for ammonia catalytic oxidation

This work considers the oxidation of ammonia (NH₃) by selective catalytic oxidation (SCO) over a CuO/La₂O₃ composite catalyst at temperatures between 150 and 400 °C. A CuO/La₂O₃ composite catalyst was prepared by co-precipitation of copper nitrate and lanthanum nitrate at various molar concentrations. This study also considers how the concentration of influent NH₃ (C₀ = 1000 ppm), the space velocity (GHSV = 92,000 l/h), the relative humidity (RH = 12%) and the concentration of oxygen (O₂ = 4%) affect the operational stability and the capacity for removing NH₃. The catalysts that were characterized using FTIR, XRD, UV-Vis, BET and PSA, have shown that the catalytic behavior is related to the copper (II) oxide, while lanthanum (III) oxide may serve only to provide active sites for the reaction during a catalyzed oxidation run. The experimental results show that the extent of conversion of ammonia by SCO in the presence of the CuO/La₂O₃ composite catalyst was a function of the molar ratio. The ammonia was removed by oxidation in the absence of CuO/La₂O₃ composite catalyst, and around 93.0% NH₃ reduction was achieved during catalytic oxidation over the CuO/La₂O₃ (8:2, molar/molar) catalyst at 400 °C with an oxygen content of 4.0%. Moreover, the effect of the reaction temperature on the removal of NH₃ in the gaseous phase was also monitored at a gas hourly space velocity of under 92,000 h^− 1.     

固定床内错流传热——I.床层的温度分布

对固定床中流体与换热管呈错流流动的传热进行了实验研究,并以二维传热模型进行模拟.比较模拟结果与实验测得数据得到如下结论:错流传热影响区域主要在换热管的后方,在前方几乎没有影响;错流传热过程与流体流动方向密切相关,热量传递顺流体流动方向进行,逆流动方向几乎不发生热量传递;随着Reynolds数增大,等温线范围变窄,被加热区宽度变小.拟合关联得到了壁给热系数hw和床层有效导热系数lb的关系式:hwDP/lf=14.77+0.058RePr,l/l=15.14+0.296RePr.     

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。     

Mass transfer mechanisms in fixed-bed adsorption of erythromycin

The equilibrium and kinetic characteristics of the adsorption of erythromycin to Sepabeads SP825 were determined. The equilibrium data in a batch system was well described by a Langmuir isotherm. The separation performance was investigated in a fixed-bed system with respect to the adsorption superficial velocity, ionic strength and pH. A mathematical model was used to simulate the mass transfer mechanism, taking film mass transfer, pore diffusion and axial dispersion into account. The model predictions were consistent with the experimental data and were consequently used to determine the mass transfer coefficients.