LY-C_2-02催化剂在两段床反应器的长周期运行

中国石油天然气股份有限公司辽阳石化分公司乙烯厂220 kt·a~(-1)乙烯装置碳二加氢采用两台直列式两段反应器。每段反应器的催化剂装填量6.6 m~3,一段反应器入口物料中乙炔体积分数达到1.85%~2.30%,远高于同类装置。由于乙炔含量高,一段反应器的温升为75℃,致使一段反应器出口温度达到125℃,催化剂结焦严重,催化剂运行周期短为7个月。2010年投入应用LY-C2-02催化剂,从2012年8月至2015年5月,催化剂已连续运行超过32个月,运行状态良好,乙烯平均选择性大于45%。     

Catalytic pyrolysis of naphtha on the KVO3-based catalyst

The catalytic pyrolysis of naphtha has been performed in a quartz reactor to produce the light olefins at high yields. The catalytic pyrolysis leads to 10 and 5% higher values in the yields of ethylene and propylene, respectively, compared to the thermal pyrolysis at the same operation condition. The enhancement of olefin yield in the presence of catalyst comes from the better heat transfer through the catalyst particles. KVO₃ plays role of a catalyst to accelerate the gasification of coke deposited on the catalyst surface and its optimum range is found to be more than 10 wt.%. An addition of B₂O₃ into KVO₃-based catalyst causes a strong interaction between metal oxide (KVO₃) and -Al₂O₃ support, which decreases the loss by an evaporation of active phase.     

逆水煤气变换耦合乙烷脱氢反应中载体对氧化铬催化剂性能的影响

研究了在逆水煤气变换耦合乙烷脱氢反应中担载型氧化铬催化剂的活性,考察了多种载体对于催化剂反应性能的影响。结果表明,不同的载体所担载的氧化铬催化剂具有不同的催化性能。其中二氧化硅担载的氧化铬催化剂具有较高的乙烷转化率和乙烯选择性,在700℃时分别达到30.7%和96.5%。CO₂的作用是通过与H₂反应促进乙烷脱氢、并减少催化剂表面积炭。运用XRD、TPR、 XPS、UV-DRS和微量吸附量热技术对催化剂体相与表面结构、表面酸性和铬物种价态等进行了表征,结果显示催化剂表面酸中心适当的强度、数量和分布有利于乙烷的活化和催化转化,Cr³⁺和Cr⁶⁺物种是反应的活性中心。     

己二酸二甲酯加氢制1,6-己二醇催化剂工业侧线研究

采用共沉淀法制备新型Cu基己二酸二甲酯加氢制1,6-己二醇催化剂,在工业侧线试验装置上,考察入口温度、反应压力、氢酯物质的量比和液相空速等工艺条件的影响,完成1 000 h稳定性试验。结果表明,在入口温度210℃、反应压力≥5.0 MPa、空速(0.1~0.2)h~(-1)和氢酯物质的量比≥170条件下,己二酸二甲酯转化率大于99%,1,6-己二醇选择性97%,催化剂性能稳定,显示了良好的工业应用前景。     

Steam reforming of the aqueous fraction of bio-oil over structured Ru/MgO/Al2O3 catalysts

A catalyst consisting of Ru (5%) dispersed on 15% MgO/Al₂O₃ carrier exhibits high activity and selectivity, as well as satisfactory stability with time on stream, under conditions of steam reforming of acetic acid, a model compound for pyrolysis oil. The presence of MgO in the catalyst formulation is shown to be related to oxygen and/or hydroxyl radical spillover from the carrier to the metal particles. A series of Ru/MgO/Al₂O₃ catalysts supported on cordierite monoliths, ceramic foams and γ-Al₂O₃ pellets were prepared and tested for the production of hydrogen by catalytic steam reforming of the aqueous fraction of bio-oil. All different structural forms of the catalyst exhibited satisfactory activity, converting completely the bio-oil, good selectivity toward hydrogen and satisfactory stability with time on stream. However, the catalyst supported on pellets exhibited the best catalytic performance, among all catalysts investigated. Reforming reactions, and thus hydrogen production, are favoured at high temperatures and low space velocities. Coking is one of the most significant problems encountered in these processes. It was found that only a small part of the incoming carbon is deposited on the catalyst surface, which is mainly present as CH_x. However, coke deposition is more intense on the reactor wall above the catalytic bed, due to homogeneous polymerization of unstable ingredients of bio-oil.     

醋酸甲酯加氢制乙醇催化剂工业侧线试验

针对聚乙烯醇行业副产大量粗醋酸甲酯的加氢利用需求,采用络合沉淀组装法制备新型Cu-M/SiO2催化剂。对催化剂进行扩大试验,采用工业侧线试验装置考察入口温度、反应压力、氢酯物质的量比和空速等的影响,完成3200h稳定性试验。结果表明,在入口温度≥215℃、反应压力(2.4~3.2)MPa、空速(0.4~1.0)h-1和氢酯物质的量比≥25条件下,醋酸甲酯转化率大于98.5%,乙醇选择性大于99.0%,催化剂结构和性能稳定,显示出良好的工业应用前景。     

OCM in a fixed-bed reactor: limits and perspectives

The oxidative coupling of methane (OCM) over a La₂O₃/CaO catalyst was studied in a poly tropic fixed-bed reactor (I.D. = 15 mm, W/F= 0.15 g · s/ml). Reaction conditions for stable operation were determined. (1) A minimum inlet temperature of 580°C was necessary to initiate the reaction. (2) The maximum hot-spot temperature of 1000°C limited the highest oxygen inlet concentration to 20%. The temperature gradients in the bed amounted to 250 K. The influence of the reaction conditions on the C₂₊ selectivity was investigated by testing the effects of temperature (T_inlet = 580–860°C), oxygen concentration (C_O2 = 5–20%) and particle diameter (d_p = 250–350 μm, and pellets of h_p = 4 mm and d_p = 4 mm). The C₂₊ selectivity ran through a maximum with increasing temperature and decreased with rising inlet oxygen concentration. Mass-transfer limitations, which occurred when applying pellets, resulted in a drop of C₂₊ selectivity. Highest C₂₊ yields amounted to 15.5% (X_CH4 = 31%, S ₂₊ = 51%). Distributed feed of oxygen was tested as a means to cope with the high temperature gradients and to increase C₂₊. selectivity. Upon applying this mode of operation, oxygen concentrations up to 30% could be converted. However, no improvement of C₂₊ selectivity and yield compared to cofeed operation was achieved.     

Production of hydrogen for fuel cells by reformation of biomass-derived ethanol

The reformation of biomass-derived ethanol to a hydrogen-rich gas stream suitable for feeding fuel cells is investigated as an efficient and environmentally friendly process for the production of electricity for mobile and stationary applications. Steam reforming of ethanol is investigated over Ni catalysts supported on La₂O₃, Al₂O₃, YSZ and MgO. The influence of several parameters on the catalytic activity and selectivity is examined including reaction temperature, water-to-ethanol ratio and space velocity. Results reveal that the Ni/La₂O₃ catalyst exhibits high activity and selectivity toward hydrogen production and, most important, long term stability for steam reforming of ethanol. The enhanced stability of this catalyst may be due to scavenging of coke deposition on the Ni surface by lanthanum oxycarbonate species which exist on top of the Ni particles under reaction conditions.     

碳二前脱丙烷前加氢催化剂工艺条件试验

采用浸渍法制备Pd-Ag/α-Al2O3催化剂,采用碳二前脱丙烷前加氢工艺系统考察反应器入口温度、空速和反应压力对催化剂性能的影响。结果表明,随着反应器入口温度升高,乙炔和丙炔+丙二烯转化率提高,乙烯选择性提高至一定值后趋于稳定,丙烯选择性波动不大,正丁烯生成量增加,较为适宜的反应器入口温度为(60~70)℃;随着空速升高,乙炔和丙炔+丙二烯转化率降低,乙烯选择性提高,丙烯选择性变化不大,正丁烯生成量降低,较为适宜的空速为(12 000~14 000)h-1;随着反应压力升高,乙炔转化率和丙炔+丙二烯转化率略增,乙烯选择性降低,较为适宜的反应压力为3.6 MPa。     

异丁烷脱氢过程催化剂结焦与焦性质研究

在固定床反应装置上,采用YBD型Cr/Al_2O_3催化剂催化异丁烷脱氢,通过热分析技术研究结焦催化剂,考察反应条件对催化剂结焦量及焦性质的影响。结果表明,Cr/Al_2O_3催化剂对异丁烷脱氢有较好的催化活性,当反应温度580℃,空速800 h^(-1)时,异丁烷转化率60%以上,异丁烯选择性90%以上,异丁烯收率约60%。反应温度、空速以及异丁烯对结焦催化剂的焦含量有明显影响,当反应温度超过580℃,随着原料气中异丁烯含量的增加,催化剂的结焦量迅速增加。     

载体表面羟基种类对DMO加氢用Cu/SiO2催化剂性能的影响

通过程序升温焙烧改变气相纳米二氧化硅表面的羟基含量及种类,并以其为载体,采用蒸氨法制备了Cu/SiO₂催化剂,使用比表面积测试（BET）、傅里叶变换红外光谱（FTIR）、漫反射傅里叶变换红外光谱（DRIFT）、X射线衍射（XRD）、透射电子显微镜（TEM）、H₂程序升温还原（H₂-TPR）、NH₃/CO₂程序升温脱附（NH₃/CO₂-TPD）、X射线光电子能谱（XPS）、俄歇电子能谱（AES）等方法研究了Cu/SiO₂催化剂的结构和酸碱性,采用固定床反应器在低温（448K）、低压（1.5MPa）的反应条件下进行草酸二甲酯加氢制备乙二醇的反应,评价其催化活性。结果表明,高温焙烧二氧化硅载体可显著改变后续合成Cu/SiO₂催化剂的结构并降低其酸碱性,对提高乙二醇选择性和降低草酸二甲酯加氢过程中醇类或醚类副产物的选择性具有明显的促进作用。但同时该过程会导致催化剂的活性降低,载体焙烧（473K）后合成的催化剂均需要提高氢酯比方能获得最佳反应结果。其中经873K焙烧的二氧化硅制备的Cu/SiO₂-4催化剂,在最佳反应条件下乙二醇的选择性由低温焙烧后的92%左右提升到97%以上,草酸二甲酯转化率保持在100%。     

ZSM-5@t-ZrO2制备及其对甲硫醇催化合成影响机制

采用水热包覆法和物理共混法分别制备了ZSM-5@t-ZrO₂和ZSM-5/t-ZrO₂复合催化剂,并以ZSM-5和t-ZrO₂为对比参考,研究了不同结构催化剂的物化性质和催化性能。在此基础上,借助漫反射傅里叶变换红外光谱,考察了反应温度和预硫化操作对ZSM-5@t-ZrO₂复合催化剂上甲醇和硫化氢反应分子吸附转化的影响。结果表明,水热包覆环境修饰了ZSM-5@t-ZrO₂复合催化剂的物化性质,提升了甲醇硫醇化反应的催化性能和抗积碳积硫失活能力。在反应压力1 MPa、反应温度380 ℃、预硫化1 h、N₂流量100 mL/min的条件下,甲醇转化率、甲硫醇选择性及甲硫醇收率分别达到92.02%、90.56%和82.76%。硫化氢分子在ZSM-5@t-ZrO₂催化剂的碱位上吸附解离为巯基,进而攻击甲氧基,这是甲硫醇合成反应的速率控制步骤。380 ℃的反应温度和预硫化操作有助于构建形成匹配的甲氧基和巯基生成速率,在提高催化性能的同时还可有效降低积碳积硫形成速率。     

Production of gasoline range hydrocarbons from catalytic reaction of methane in the presence of ethylene over W/HZSM-5

The catalytic conversion of a methane and ethylene mixture to gasoline range hydrocarbons has been studied over W/HZSM-5 catalyst. The effect of process variables, such as temperature, percentage of volume of ethylene in the methane stream and catalyst loading on the distribution of hydrocarbons was studied. The reaction was conducted in a fixed-bed quartz-micro reactor in the temperature range of 300–500 °C using percentage of volume of ethylene in methane stream between 25 and 75% and catalyst loading of 0.2–0.4 g. The catalyst showed good catalytic performance yielding hydrocarbons consisting of gaseous products along with gasoline range liquid products. The mixed feed stream can be converted to higher hydrocarbons containing a high-liquid gasoline product selectivity (>42%). Non-aromatics C₅–C₁₀ hydrocarbons selectivity in the range of 12–53% was observed at the operating conditions studied. Design of experiment was employed to determine the optimum conditions for maximum liquid hydrocarbon products. The distribution of the gasoline range hydrocarbons (C₅–C₁₀ non-aromatics and aromatics hydrocarbons) was also determined for the optimum conditions.     

碳二前脱丙烷前加氢催化剂PEC-21在中国石油大庆石化公司的工业试验

由中国石油石油化工研究院自主开发的碳二前脱丙烷前加氢催化剂PEC-21在中国石油大庆石化公司270 kt·a^-1装置上首次工业试验,工业试验期间催化剂表现出开工时间短和开工稳定性好的特点;1 600 h长周期运行期间,在一段反应器反应压力3.5 MPa和入口温度64.5 ℃工艺条件下,平均乙炔转化率55.7%,乙烯选择性94.8%,丙烯选择性97.8%,表明PEC-21催化剂具有优异的活性、选择性及稳定性,整体运行性能达到国际先进水平。     

Comparison of behaviour of rare earth containing catalysts in the oxidative dehydrogenation of ethane

Catalyst promotion by addition of either La and Sm to MgO or Na aluminate to Sm₂O₃ and La₂O₃ has been investigated for the oxidative dehydrogenation of ethane in the temperature range 550–700°C. With all unpromoted and promoted catalysts, the selectivity to ethylene is strongly enhanced by the temperature, the highest values being obtained at 700°C. Sm₂O₃ is the most active among the bulk oxides, while samarium addition to MgO results in higher surface area, but does not enhance the catalytic activity. Ethylene productivity on La₂O₃ promoted MgO samples is higher than with pure La₂O₃, Sm₂O₃ and MgO, not only due to the stabilising effect of La on MgO surface area, but also due to a higher intrinsic activity. With both bulk oxides and rare earth promoted MgO, the selectivity to ethylene strongly increases by decreasing the O₂/C₂H₆ feed ratio, while it is quite unaffected by ethane conversion and catalyst composition, in agreement with the hypothesis that the main role of catalyst in the experimental conditions investigated is to produce ethyl radicals which are converted in the gas phase to CO and C₂H₄. When La₂O₃ is modified by the addition of sodium aluminate the catalytic behaviour significantly changes, likely due to a different, mostly heterogeneous reaction mechanism. On aluminate promoted lanthana, ethane is converted to ethylene with higher yields which do not depend on the feed ratio. Moreover, only CO₂ is produced as by-product, the formation of CO being quite negligible.     

Ru和Cu协同催化湿式氧化处理氨氮废水

采用化学还原法制备了RuCu/TiO₂双金属催化剂,并探究了Ru和Cu的协同作用对催化湿式氧化（CWAO）无害化处理氨氮废水催化性能的影响。研究结果表明,Cu的添加可有效改善Ru/TiO₂催化剂的N₂选择性,而Ru的存在可有效提高Cu/TiO₂催化剂的催化活性。反应条件为0.5 MPa、150℃、[NH₃]₀=1000 mg·L^-1、pH=12、模拟废水处理量为33 L·（kg cat）^-1·h^-1时,1Ru2Cu/TiO₂能使废水的氨氮转化率和N₂选择性分别高达87.7%和85.9%。表征结果表明：Ru和Cu的协同在催化氧化氨氮废水过程中起了关键作用,主要体现在：Ru和Cu的强相互作用导致1Ru2Cu/TiO₂催化剂具有良好的抗流失性能,进而使得催化剂具有良好的稳定性;Ru和Cu的电子转移使得1Ru2Cu/TiO₂具有适中的亲氧性能,有效提高了催化剂的催化活性。     

DC and FCC dry gas valorization on PtZrGa/MCM-41

The light olefins present in DC and FCC dry gas can be valorized into aromatics and paraffins. A new PtZrGa/MCM-41 catalyst has been synthetized and used to carry out dimerization and trimerization reactions of olefins. The catalyst was characterized by XRD and using FTIR, XPS, ⁷¹Ga and ¹H NMR spectroscopies. A blend of ethylene–propylene in presence of CS₂, hydrogen and benzene were tested in a semi-batch-type reactor. A simplified set of reaction is proposed and the operating variables were explored to study the catalytic activity and selectivity. The paper discusses the catalytic surface composition and the sensitivity of the reactions to temperature, hydrogen partial pressure and ethylene/propylene ratio. The catalyst deactivation was analyzed and the industrial implication was discussed.     

CeO2复合改性ZSM-5分子筛用于催化甲醇制丙烯研究

在甲醇制丙烯(MTP)反应中,ZSM-5分子筛较强的酸性易使甲醇与ZSM-5接触发生氢转移、芳构化等二次反应,堵塞孔道,使得其微孔结构更加不利于分子的扩散,加速催化剂积碳失活,导致丙烯选择性和丙烯/乙烯(P/E)比值下降。因此,本文利用催化活性较高的CeO₂对ZSM-5分子筛进行复合改性以达到有效降低其酸性并增大介孔的目的来提高丙烯选择性和P/E比。通过XRD、NH₃-TPD和N₂吸脱附技术表征,研究了不同ZSM-5硅铝比(摩尔比)、两相质量比(m(CeO₂)/m(ZSM-5))对CeO₂/ZSM-5复合催化剂物化性质的影响。在反应温度480 ℃、重时空速2.6 h^-1、N₂流量100 mL·min^-1、常压纯甲醇进料的条件下,考察了所制备的复合催化剂催化MTP的性能。结果表明,硅铝比为250、m(CeO₂)/m(ZSM-5)为1∶4的复合催化剂比以往研究结果具有更优异的MTP催化性能,甲醇转化率为99.9%,丙烯选择性为42.78%,P/E比为6.3。     

Transient modeling of combined catalytic combustion/CH4 steam reforming

This paper presents an investigation into the complex interactions between catalytic combustion and CH₄ steam reforming in a co-flow heat exchanger where the surface combustion drives the endothermic steam reforming on opposite sides of separating plates in alternating channel flows. To this end, a simplified transient model was established to assess the stability of a system combining H₂ or CH₄ combustion over a supported Pd catalyst and CH₄ steam reforming over a supported Rh catalyst. The model uses previously reported detailed surface chemistry mechanisms, and results compared favorably with experiments using a flat-plate reactor with simultaneous H₂ combustion over a γ-Al₂O₃-supported Pd catalyst and CH₄ steam reforming over a γ-Al₂O₃-supported Rh catalyst. Results indicate that stable reactor operation is achievable at relatively low inlet temperatures (400 °C) with H₂ combustion. Model results for a reactor with CH₄ combustion indicated that stable reactor operation with reforming fuel conversion to H₂ requires higher inlet temperatures. The results indicate that slow transient decay of conversion, on the order of minutes, can arise due to loss of combustion activity from high-temperature reduction of the Pd catalyst near the reactor entrance. However, model results also show that under preferred conditions, the endothermic reforming can be sustained with adequate conversion to maintain combustion catalyst temperatures within the range where activity is high. A parametric study of combustion inlet stoichiometry, temperature, and velocity reveals that higher combustion fuel/air ratios are preferred with lower inlet temperatures (≤500 °C) while lower fuel/air ratios are necessary at higher inlet temperatures (600 °C).     

Selective hydrogenation of acetylene over Pd/CeO2

Five hundred ppm Pd/CeO₂ catalyst was prepared and evaluated in selective hydrogenation of acetylene in large excess of ethylene since ceria has been recently found to be a reasonable stand-alone catalyst for this reaction. Pd/CeO₂ catalyst could be activated in situ by the feed gas during reactions and the catalyst without reduction showed much better ethylene selectivity than the reduced one in the high temperature range due to the formation of oxygen vacancies by reduction. Excellent ethylene selectivity of ~100% was obtained in the whole reaction temperature range of 50°C–200°C for samples calcined at temperatures of 600°C and 800°C. This could be ascribed to the formation of Pd_xCe_1−xO_2−y or Pd-O-Ce surface species based on the X-ray diffraction and X-ray photoelectron spectroscopy results, indicating the strong interaction between palladium and ceria.