氧化钴/高炉渣催化剂的丙烷氧化脱氢性能

以攀钢高炉渣为载体,采用固体研磨法负载氧化钴,制备了氧化钴/高炉渣负载型催化剂,并以XRD、 H2-TPR技术对催化剂进行表征,研究了其对丙烷氧化脱氢制丙烯反应的催化性能.实验结果表明氧化钴负载在高炉渣上提高了丙烯选择性,氧化钴的负载量为20%时催化剂表现较好的催化性能,在550℃时丙烷转化率为28.80%,丙烯选择性为35.51%.本实验为资源综合利用及减少环境污染提供了新方法.     

羰基化石墨片催化丙烷氧化脱氢制丙烯

以资源丰富的石墨片为原材料, 通过简单的气相氧化处理制得羰基化石墨片, 并发现羰基化石墨片可以高选择性催化丙烷氧化脱氢制丙烯: 当丙烷转化率为12.4%时, 丙烯的选择性高达73.9%, 且副产物乙烯的选择性为13%。羰基化石墨片优良的烯烃选择性远超利用相同气相氧化处理的碳管, 并且可以媲美目前催化性能最优的六方氮化硼材料。催化剂具有良好的稳定性, 在505 ℃的反应温度下, 经过48 h的氧化脱氢反应测试后, 催化剂性能无明显的衰减。多种表征技术表明: 气相氧化处理不会破坏石墨片的结构, 且保留了石墨自身的高温抗氧化性, 而经过气相氧化处理羰基官能团的比例大幅度提高, 羰基作为活性位与丙烷中的氢原子发生反应, 自身形成羟基而丙烷则转换为丙烯, 羟基在高温下与氧原子反应生成为羰基, 从而完成催化剂的重生, 继续下一个循环。这种发生在催化剂表面的可控催化方式, 保证了丙烷氧化脱氢过程中选择性生成丙烯, 避免了深度氧化。另外, 石墨材料的来源广泛, 成本低, 作为催化剂可以极大地推动丙烷氧化脱氢的工业化。     

负载型MoO3／β分子筛催化剂的丙烷氧化脱氢性能

以β分子筛为载体,采用浸渍法负载钼制备了MoO3／β筛催化剂,通过XRD、FTIR、BET、NH3-TPD进行表征,结果表明,样品中有活性组分氧化钼存在,也有不同酸性质的活性位存在,负载量对催化剂的表面积和孔径有影响;考察了催化剂对丙烷氧化脱氢制丙烯的催化性能,结果表明,单纯β分子筛载体有催化活性,不同钼负载量对催化性能有影响,考察负载量区间内反应转化率出现极值。     

钒基催化剂上丙烷氧化脱氢催化性能研究进展

低碳烷烃作为一种资源丰富且廉价的原料,利用其可制取具有高附加值的烯烃和含氧衍生物,对缓解丙烯和石油资源短缺具有重要的价值。但丙烷在高温下易深度氧化和深度裂解,且催化剂易积碳失活,使得丙烯选择性降低,故迫切需要开发低温高效的催化剂。简要介绍了丙烷氧化脱氢制丙烯的研究意义和钒基催化剂上丙烷氧化脱氢反应的机理,综述了负载型钒基催化剂的载体类型及性质、活性物种引入方式、表面钒物种的还原性能、钒负载量、氧化剂的选择对丙烷氧化脱氢催化活性及对丙烯选择性的影响。     

富氢气氛中CO选择性氧化CuO/CeO2催化剂的研究

选择负载型铜催化剂为研究对象,以富氢条件下研究CO选择性氧化反应为导向,考察了反应气氛、焙烧温度、CuO含量及Al2O3掺杂对CuO/CeO2催化剂的CO选择性氧化催化性能的影响,并采用TEM表征技术探讨结构与性能的关系。     

盐酸改性V_2O_5/TiO_2及其催化甲醇选择性氧化的研究

对TiO2负载V2O5催化剂进行盐酸改性制得了HC-V/TiO2催化剂,并将其应用于甲醇选择性氧化制二甲氧基甲烷(DMM)。V2O5负载量为10%的催化剂10V/TiO2上,钒氧物种具有良好的分散性。对10V/TiO2进行不同量的盐酸改性制备了HC-10V/TiO2催化剂,对其进行XRD、UV-Vis、H2-TPR、NH3-TPD表征。结果表明,适量的盐酸改性能有效改善催化剂的酸性,但对钒氧物种的分散性和还原性没有影响,改性后催化剂的反应活性和稳定性也得到很大提高,甲醇转化率和DMM选择性明显增加。Cl-负载量为4%的催化剂4HC-10V/TiO2在反应温度160℃时,甲醇的转化率为77.60%,DMM的选择性高达78.31%。     

焙烧温度对Cu-Mn/γ-Al_2O_3催化剂催化氧化甲苯性能的影响

采用浸渍法合成了Cu-Mn/γ-Al2O3催化剂,通过XRD、BET、H2-TPR和XPS等方法对经不同温度(300~600℃)焙烧的催化剂进行表征,采用固定床管式反应装置考察了焙烧温度对催化剂催化氧化甲苯的影响,并讨论活性组分、表面Cu+/(Cu++Cu2+)和Mn4+/(Mn4++Mn3+)摩尔比值与催化剂活性的关系。结果发现,550℃焙烧温度的催化剂活性最好,氧化能力最强,其转化率为95%时对应的反应温度T95(286℃)最低,CO2的选择性达100%。在550℃焙烧时生成的Cu1.4Mn1.6O4新相以及催化剂表面中相对含量更高的Cu+和Mn4+是催化剂具有高活性的主要原因。     

Pt/TiO_2纳米薄膜的制备及光催化气相甲醇制氢的研究

通过溶胶-凝胶法制备了Pt/TiO2纳米薄膜,并在气相连续流动装置中,对甲醇的光催化脱氢反应进行了研究。将Pt/TiO2薄膜催化剂与TiO2薄膜催化剂的光催化活性进行了比较,考察了产氢量甲醇浓度、光照时间的关系,以及空速、反应温度对甲醇转化率的影响。结果表明,经过还原后分散于TiO2薄膜表面的Pt是以Pt2+及Pt0价态存在的。Pt/TiO2纳米薄膜是未负载Pt的纳米薄膜光催化活性的28倍。增加甲醇蒸汽的浓度会使产氢速率增大;当甲醇浓度在29%时,产氢速率达到最大,为4.68mmol/h。醇的转化率随着空速的增加而减小。该反应在一定的浓度范围内是一级反应,其反应的活化能为26.19kJ/mol。     

流化床CVD法制备单壁碳纳米管:反应温度与时间的影响

基于负载法Fe—MgO体系催化剂研究了化学气相沉积（CVD）法在流化床反应器中反应温度和时间对单壁碳纳米管（SWCNTs）生长的影响。通过气相色谱对尾气进行实时在线分析，获得了CH4在反应过程中的转化率随时间的变化规律。并对不同反应温度和反应时间所获产品进行了TEM、Raman和TGA等表征。结果表明，900℃是最佳的反应温度，反应温度过低会降低催化剂活性，反应温度过高则容易使催化剂过快失活。在合适的反应温度下，反应前10min催化剂的平均活性较高，能够得到较高质量的SWCNTs，10min后催化剂基本失活。     

汽油氧化重整制氢反应镍催化剂的实验研究

在小型固定床反应器中,考察了汽油氧化重整制氢反应体系中镍催化剂 的催化性能。实验考察了镍/三氧化二铝催化剂,活性组分镍含量对汽油氧化重整制氢反应的影响,实验还考察了镍/三氧化二铝催化剂中加入贵金属助剂的催化性能。实验结果表明单组元镍/三氧化二铝催化剂对汽油氧化重整制氢反应在反应温度低于650℃时,其活性较低,生成氢气的选择性也不高;反应温度高于650℃时,其反应活性及生成氢的选择性有明显的提高。镍/三氧化二铝催化剂中加入贵金属组分作为助催化剂制成的双金属催化剂在汽油制氢反应中的催化活性及生成氢的选择性均有明显的提高。     

Optimization of process parameters for transalkylation of toluene to xylene using response surface methodology

ABSTRACT

H-beta zeolite was modified by the ion exchange method to replace its H⁺ ions with Ce⁴⁺ ions. The catalytic performance of this cerium exchanged beta zeolite was evaluated for vapor phase transalkylation of 1,2,4 TMB (1,2,4 trimethylbenzene) with toluene for the production of xylene in a fixed bed, down-flow reactor. The modified zeolite was found to be highly active for this transalkylation reaction. The response surface methodology (RSM) is used for designing the experiments. The effect of three important reaction parameters viz. temperature, reactant ratio, and space time on response variables (toluene conversion and xylene selectivity) is studied and discussed. All the three selected reaction parameters were found to be significant for the toluene conversion; whereas, xylene selectivity was not much influenced by the temperature. The optimum values of the reaction parameters predicted by the model (temperature: 409.7°C, reactant ratio: 2.024, and space time: 4.451) were validated by an experimental run. The results of the experimental run were in close agreement with the model predicted results.     

Performances analysis of a compact kW-scale ATR reactor for distributed H2 production

The distributed production of hydrogen takes on a growing consensus among the different methods for feeding fuel cells. The auto-thermal reforming of hydrocarbons is a candidate as the best method for producing hydrogen on a small scale. Since auto-thermal reforming reactor is fed with hydrocarbon, water and air, their mixing may play a fundamental role on the final process performances, by influencing hydrocarbon conversion, reaction selectivity, and hydrogen production. To obtain a very compact reaction system, reactants pre-heating and products cooling were realized in a special heat exchange system, fully integrated in the reactor. To study the reaction trend along the catalytic bed, a multipoint analysis system was set-up, allowing to monitor both temperature and composition in several points of catalytic bed, and then in several space velocity conditions. The preliminary tests showed very short start-up time, and fast response to the feed variations, confirming that the proposed reaction system is an interesting solution for distributed and non-continuous hydrogen production.     

Ni-Pd纳米涂层整体式催化剂加氢性能研究

采用浸涂法将自制的介孔空心SiO2纳米粉体涂覆到堇青石基体上,然后采用微波法负载活性组分Pd和助剂Ni制备了纳米涂层整体式加氢催化剂,并考察空速、涂层增重、Ni助剂添加量等因素对其乙炔选择性加氢催化性能的影响。结果表明:经过涂覆后的堇青石整体式催化剂加氢性能与未涂覆时相比有了显著提高,且添加适量的助剂Ni有助于催化性能的进一步改进。在反应温度为54℃、压力为0.1 MPa、空速为3 800 h-1的条件下,使用涂层增重质量分数为6%、Ni与Pd物质的量比为4∶1的催化剂,当乙炔接近完全转化时,乙烯选择性能够到达40.9%。     

活性炭负载CaCl2催化五氯乙烷脱HCl的研究

筛选出了催化性能较好的活性炭负载氯化钙(CaCl2/AC)催化剂用于五氯乙烷脱HCl制备四氯乙烯。考察了反应温度、空速、CaCl2负载量对CaCl2/AC催化剂催化性能的影响及催化剂的稳定性。实验结果表明最佳反应条件:反应温度为240℃,空速为3.4h-1,CaCl2负载量为0.3mmol/g,在此反应条件下五氯乙烷的转化率可达99%以上,四氯乙烯的收率达95%以上,催化剂催化性能重现性良好。采用X射线衍射(XRD)、氮气吸附-脱附对催化剂进行了表征。结果表明CaCl2在活性炭表面分散良好;随着CaCl2负载量的增加,CaCl2/AC催化剂的BET比表面及孔容逐渐减小。     

催化剂MnCe（y）Ox/TiO2的制备及其催化燃烧甲苯的活性

以TiO2为载体,采用浸渍法制备了不同配比的MnCe复合型催化剂,并采用X射线衍射(XRD)、氧气的程序升温脱附(O2-TPD)和氢气的程序升温还原(H2-TPR)对制备的催化剂进行表征,比较了催化剂催化氧化(燃烧)甲苯的活性。研究结果表明,所制备的催化剂MnCe(y)Ox/TiO2对甲苯有明显的催化活性。当Ce/(Mn+Ce)的摩尔比为0.1时,催化剂MnCe(0.1)Ox/TiO2的催化活性最高,甲苯的转化率达到90%时的温度为254℃。在催化剂MnOx/TiO2中掺杂少量的Ce元素,有利于活性组分Mn物种在载体表面上以更小颗粒而且更高的分散度存在,从而提高催化剂的催化活性。     

不同粒度β沸石的催化性能

采用不同粒度的β沸石为关键组分制备成催化剂,以正庚烷为原料,在连续流动固定床微型反应器上进行加氢裂化性能评价,结果表明,在相同反应温度下,β沸石粒度减小,转化率明显提高,异构选择性降低,但相同转化率下的异构选择性基本相当。     

Selective formation of ethyltoluene by alkylation of toluene with ethanol over modified HZSM-5 zeolites

The selective formation of para-ethyltoluene using toluene and ethanol was studied using unmodified as well as modified shape-selective HZSM-5 catalysts. The reaction was carried out in a fixed-bed reactor in the temperature range 573–723 K and atmospheric pressure. The effect of reaction temperature, steaming temperature, and toluene-to-ethanol mole ratio on the conversion, activity, and selectivity were studied over unmodified and modified HZSM-5 zeolites. The parent zeolite HZSM-5 was modified by inorganic additives such as phosphorus, magnesium, and boron using ion-exchange and impregnation techniques.The experimental data were analyzed and reaction models were proposed based on the Langmuir-Hinshelwood-Hougen-Watson approach (LHHW) and the Eley-Rideal mechanism. The modification of HZSM-5 resulted in an increase of activation energy from a value of 61.78 kJ/mol (unmodified HZSM-5) to 97.03 kJ/mol (Mg-HZSM-5). The increase in apparent activation energy of the modified catalyst is attributed to the lower acid strength and not to the decreased number of acid sites responsible for the alkylation reaction.     

Catalytic performance of nanosized Pt-Au alloy catalyst in oxidation of methanol and toluene

The alloy formed between a group-VII metal such as platinum and a group-IB metal such as gold changes the catalytic behavior compared to the monometallic phase, increasing the selectivity toward certain products and also decreasing the deactivation rate. Pt-Au alloy nanoparticles coated on alumina support were found to be catalytically very active for complete oxidation of methanol and toluene. Furthermore, the nanosized Pt-Au particles were added to ZnO/Al2O3 on monolith catalyst. Also, effect of various parameters such as concentration of methanol and toluene and feed flow rate was investigated. Au particles were sized in 20 approximately 30 nm and Pt particles were well dispersed. In case of alumina supported powder catalyst, complete oxidation of methanol occurred at a temperature lower than that of toluene. From oxidation activity of monolithic honeycomb with Pt and Au particles, the conversion of methanol was increased with increasing the concentration of methanol, but conversion of toluene showed a decreasing tendency as the concentration of toluene increased. Also, conversion of methanol over honeycomb catalyst was not largely affected by feed flow rate, while conversion in toluene oxidation was decreased rapidly as feed flow rate was increased. As a result, the Pt-Au/ZnO/Al2O3/M catalyst used is likely to efficiently treat a large volume of exhaust gas containing VOCs.     

Synthesis of SnO(Sn)/Ni foam monolithic catalysts and their catalytic activity

以泡沫镍为载体制备一系列活性组分为SnO和Sn的整体催化剂,测定了催化剂对邻苯二甲酸二(2-乙基己)酯(DOP)合成反应的催化活性,研究了电镀电流密度、电镀温度和焙烧处理对催化性能的影响,以及整体催化剂的寿命和失活的原因. 结果表明,所制备的SnO(Sn)/泡沫镍整体催化剂对DOP的合成有很好的催化活性和选择性.用整体催化剂Sn/Ni-3(300)催化DOP的合成反应,在1h的反应时间内邻苯二甲酸酐的转化率达到96.75%;反应平衡时合成的产物中DOP的选择性达到97%以上.SnO(Sn)/泡沫镍整体催化剂使用后很容易从反应体系中分离,不需要任何处理即可重复使用多次.     

Effect of pretreatment conditions on particle size of bimetallic pt-au catalysts supported on ZnO/Al2O3 and its activity for toluene oxidation

Bimetallic Pt-Au catalysts supported on ZnO/Al2O3 were prepared by incipient wetness impregnation (IW-IMP) method with different pretreatment conditions such as flow velocity, calcination temperature, and heating rate under H2 during the calcination procedure, and characterized by X-ray diffraction (XRD), CO chemisorption, and scanning transmission electron microscopy (STEM) equipped energy dispersive spectroscopy (EDS). Furthermore, catalytic activity for complete oxidation of toluene was measured using a flow reactor under atmospheric pressure. Finally, relationship between the particle sizes with pretreatment conditions and catalytic activity for toluene on the bimetallic Pt-Au catalysts was discussed. In these results, nanosized bimetallic Pt-Au particles on ZnO/Al2O3 could be prepared by IW-IMP method. Relationship between the Pt and Au particle size and activity for toluene oxidation was clearly observed.