环烷烃催化裂解制低碳烯烃研究进展

综述了不同环烷烃催化裂化反应途径及主要影响条件,在催化裂解下双环及多环的开环反应容易发生,生成含单环环烷烃的裂解产物。在环烷烃的转化当中存在裂化反应和氢转移的竞争关系,当环烷烃与链烷烃共存时,会影响链烷烃的低碳烯烃收率和选择性。环烷烃催化裂解制低碳烯烃的关键是单环环烷烃的开环和抑制氢转移反应。用于富含环烷烃原料催化裂解的催化剂应具有高的开环和裂化能力以及低的氢转移能力。     

碳五烃催化裂解制取丙烯/乙烯反应性能

以ZSM-5分子筛为催化剂,碳五烃混合物为裂解原料,考察空速对碳五烃催化裂解制丙烯/乙烯反应性能的影响。结果表明,在580℃和实验空速范围,随着空速的增加,碳五烷烃及烯烃转化率整体呈下降趋势,但碳五烯烃转化率远高于碳五烷烃。乙烯及丙烯收率在空速3 h-1时达到最大,分别为10.51%和13.02%。碳四烯烃收率随空速的升高而降低,但各丁烯异构体相对于总烯烃的质量分布接近热力学平衡态。     

反应温度对汽油催化裂解多产低碳烯烃的影响

利用自制的多产低碳烯烃催化剂在小型固定流化床装置上对催化裂化汽油、焦化汽油和直馏汽油的催化裂解性能进行了实验研究,考察了反应温度对催化裂解产物分布和低碳烃收率的影响.实验结果表明焦化汽油、催化汽油和直馏汽油最佳的催化裂解反应温度分别为580、600℃和680℃,随着反应物活性的降低而显著增加.乙烯的收率随着反应温度的升高呈抛物线增长;烯烃与正构烷烃有协同反应作用,烯烃能够加速正构链烷烃的反应速率;在烯烃存在下,芳烃会生成大量的焦炭;烯烃和链烷烃是生成低碳烯烃的主要来源,是催化裂解的理想组分;最佳催化裂解的反应物为催化汽油或者焦化汽油的轻馏分与直馏汽油的轻馏分的混合物.     

石脑油催化裂解制低碳烯烃技术进展及其技术经济分析

阐述了石脑油催化裂解制低碳烯烃的机理;石脑油催化裂解催化剂体系,包括金属氧化物催化剂、沸石分子筛催化剂和复合催化剂及近年来国内外石脑油催化裂解催化剂的科研成果．并对石脑油生产低碳烯烃的催化裂解和蒸汽裂解两种工艺路线进行对比,表明石脑油催化裂解具有先进性,该领域的研究开发具有相当重要的意义。     

低碳烷烃催化转化制取低碳烯烃反应工艺的研究进展

低碳烷烃催化转化制取低碳烯烃可以大大提高低碳烷烃的附加值,因此,受到石油化工和催化领域的广泛关注。对近年来国内外有关低碳烷烃选择氧化制烯烃、低碳烷烃催化裂解制烯烃以及低碳烷烃催化脱氢制烯烃等催化反应过程的催化剂体系、反应工艺流程和催化反应器的设计等方面的研究进展进行评述,并对该领域的研究发展方向作了展望。     

甲醇制烯烃再生催化剂催化裂解混合碳四的可行性分析

随着开工建设及运行的甲醇制烯烃工业装置越来越多,如何利用碳四并将其转化为低碳烯烃变得越来越重要。为探究甲醇制烯烃再生催化剂裂解混合碳四的可行性,首先,对甲醇制烯烃工业装置副产混合碳四与石脑油蒸汽裂解和炼油催化裂化产生的碳四产品组分进行分析,得出甲醇制烯烃工业装置副产的混合碳四中烯烃含量较高且无丁二烯的结论;其次,梳理碳四催化裂解转化的研究成果,得出SAPO-34及ZSM-5分子筛都可以作为裂解碳四的催化剂且ZSM-5分子筛性能更优的结论;再者,对混合碳四转化工艺,即以碳四烯烃歧化反应和催化裂解为主的工艺进行分析与对比,总结各种工艺的特点。最终得出结论:利用高温再生催化剂裂解甲醇制烯烃副产的混合碳四是可行的,无需再建设反应器及再生器,可节省成本,具有一定的优势和经济效益,但下游烯烃分离系统处理碳四的能力会影响碳四的裂解负荷。     

轻汽油催化裂解反应研究

对高硅铝比ZSM-5分子筛进行成型和改性制得催化剂,并应用于轻汽油催化裂解制低碳烯烃反应。借助XRD、SEM、N_2吸附-脱附和NH_3-TPD等表征手段研究了分子筛原料和裂解催化剂的结构特征。实验结果表明,高于500℃的温度条件下,轻汽油中烯烃可以在催化剂上直接裂解,生成包括乙烯、丙烯和丁烯在内的低碳烯烃。原料组成对轻汽油催化裂解反应的产物分布影响明显,烯烃含量较高且碳数较低的原料更有利于反应的进行。高温和低空速有助于轻汽油转化和低碳烯烃生成。在温度540℃,压力0.05 MPa和质量空速16 h~(-1)的条件下,轻汽油中烯烃转化率可达69%,低碳烯烃总产率超过87%。     

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。     

SAPO-34分子筛应用研究进展

综述了SAPO-34分子筛催化低碳物转化制低碳烯烃(甲醇、二甲醚、卤化烷烃制烯烃、乙醇脱水制乙烯)、C_4～C_8直链烯烃/烷烃裂解制低碳烯烃、烷烃氧化或直接脱氢反应制烯烃、催化烃类或H_2选择性还原NO_x、制备膜分离材料以及在发光体材料等领域中的应用。系统分析sAPO-34分子筛在各领域应用进展,有利于理解材料的物化性能对其催化性能、热稳定性及水热稳定性、选择性渗透和分子筛分离性能的影响,有利于实现对SAPO-34分子筛的认识取得突破性进展,拓展SAPO-34分子筛应用领域,并为其他催化材料的设计提供借鉴。     

催化裂解制低碳烯烃的研究及工业应用

文章详细叙述了催化裂解制低碳烯烃的反应机理、催化裂解催化剂的分类与近几年的研究成果,讨论了影响催化裂解反应产物分布的因素,举例介绍了近十年来开发研究的新型催化裂解制低碳烯烃工艺和国内外催化裂解工业的发展情况。     

双金属改性ZSM-5-USY复合分子筛催化裂解正己烷制备低碳烯烃

为了获得催化裂解制备低碳烯烃的高效催化剂,以等体积浸渍法制备了系列单金属(Ce, Y, Zr, Mn, Cu)及双金属(Zr-Ce, Mn-Ce, Y-Ce, Cu-Ce)改性ZSM-5-USY复合分子筛催化剂,通过XRD, NH3-TPD, BET等方法表征了其物理化学性质,并将所制备催化剂用于催化裂解正己烷。结果表明,催化剂的弱酸量越多,正己烷转化率及C2~C4烯烃选择性越高,Zr-Ce共改性分子筛的催化活性较优。水蒸气处理对Zr-Ce/ZSM-5-USY催化剂的酸性及催化裂解产物分布有较大影响,经水蒸气处理的催化剂性能更稳定,可将裂解产物中低碳烯烃的选择性由20.02% (催化剂未经水蒸气处理)提高到57.55% (催化剂经水蒸气处理4 h)。研究了0.25% Zr-0.5% Ce/ZSM-5-USY催化体系的裂解反应动力学,正己烷裂解为一级反应,裂解活化能为88.93 kJ/mol。     

Thermodynamic analysis of reaction pathways and equilibrium yields for catalytic pyrolysis of naphtha

The chain length and hydrocarbon type significantly affect the production of light olefins during the catalytic pyrolysis of naphtha. Herein, for a better catalyst design and operation parameters optimization, the reaction pathways and equilibrium yields for the catalytic pyrolysis of C_5–8 n/iso/cyclo-paraffins were analyzed thermodynamically. The results revealed that the thermodynamically favorable reaction pathways for n/iso-paraffins and cyclo-paraffins were the protolytic and hydrogen transfer cracking pathways, respectively. However, the formation of light paraffin severely limits the maximum selectivity toward light olefins. The dehydrogenation cracking pathway of n/iso-paraffins and the protolytic cracking pathway of cyclo-paraffins demonstrated significantly improved selectivity for light olefins. The results are thus useful as a direction for future catalyst improvements, facilitating superior reaction pathways to enhance light olefins. In addition, the equilibrium yield of light olefins increased with increasing the chain length, and the introduction of cyclo-paraffin inhibits the formation of light olefins. High temperatures and low pressures favor the formation of ethylene, and moderate temperatures and low pressures favor the formation of propylene. n-Hexane and cyclohexane mixtures gave maximum ethylene and propylene yield of approximately 49.90% and 55.77%, respectively. This work provides theoretical guidance for the development of superior catalysts and the selection of proper operation parameters for the catalytic pyrolysis of C_5–8 n/iso/cyclo-paraffins from a thermodynamic point of view.     

Selective Deep Catalytic Cracking Process of Hydrocarbon Feedstocks for the Production of Light Olefins: II. Cooperative Effect of Thermal Cracking and Catalytic Reactions Observed in a 1-Zone Reactor

Hybrid catalysts comprising a chromium-based cocatalyst and a silica-rich ZSM-5 zeolite, when doped with lithium, showed quite a high on-stream stability even at a relatively high reaction temperature (735 °C). The cooperative effect of the thermal cracking and the catalytic reactions, and the interactions between the two catalyst components of the hybrid catalyst, resulted in maximum production of light olefins when the hybrid catalyst contained 40 wt% of zeolite. The main chemical links between the thermal cracking (TC) and the catalytic reactions were the conversions of diolefins and large olefins, the latter being produced by the TC and the active sites of the chromium-bearing cocatalyst, respectively.     

Development of Dehydrogenation Catalysts and Processes

Catalytic dehydrogenation plays an important role in production of light (C₃?CC₄ carbon range), detergent range (C₁₀?CC₁₃ carbon range) olefins and for ethylbenzene dehydrogenation to styrene. During the World War II, catalytic dehydrogenation of butane over a chromia?Calumina catalyst was practiced for the production of butenes that were dimerized to octenes and hydrogenated to octanes to yield high-octane aviation fuels. The earlier catalyst development employed chromia?Calumina catalyst and more recent catalytic developments use platinum or modified platinum catalysts. Dehydrogenation is a highly endothermic process and as such is an equilibrium limited reaction. Thus important aspects in dehydrogenation entail approaching equilibrium or near-equilibrium conversion while minimizing side reactions and coke formation.     

全结晶ZSM-5分子筛催化剂研究及工业应用

制备了全结晶ZSM-5分子筛催化剂,采用XRD、SEM、N2物理吸附-脱附及NH3-TPD等对催化剂进行表征,并考察其用于碳四烯烃催化裂解制丙烯(OCC)反应的催化性能。结果表明,制备的全结晶ZSM-5分子筛催化剂比常规成型的催化剂具有更高的结晶度、更大的比表面积、更丰富的孔结构以及更多的活性中心。高空速有利于反应的进行,提高压力对反应不利,升高温度有利于提高产物丙烯收率。在实验室研究的基础上,将全结晶ZSM-5分子筛催化剂用于OCC工业装置,取得良好的应用效果。     

烯烃裂解增产丙烯催化剂再生性能

由于烯烃裂解技术反应自身的特点,催化剂容易积炭失活,需要进行多次再生,因此,催化剂的再生性能对烯烃裂解技术至关重要。在实验室对中国石化中原石油化工有限责任公司烯烃裂解工业装置的ZSM-5催化剂进行了多次反应和再生试验,考察其烯烃裂解反应性能,并运用TG、XRD、NH₃-TPD、氮气物理吸附以及SEM等对再生前后的催化剂样品进行表征。结果表明,开发的烯烃裂解催化剂经过13次的反应再生过程,新鲜催化剂与再生催化剂的比表面积和孔容基本相同,烯烃转化率、丙烯及乙烯收率无明显变化,烯烃转化率仍大于73%,丙烯和乙烯收率分别大于32%和10%。且催化剂骨架结构和酸中心稳定,在多次反应与再生过程中的酸量保持不变,具有良好的再生性能。     

我国FCC催化剂的发展近况

阐述了国内近几年FCC催化剂在重油催化裂化、汽油降烯烃、脱硫及多产低碳烯烃方面的进展.提高抗重金属污染能力、用中孔沸石代替 ZSM-5小孔沸石及大幅度提高催化剂基质的活性仍是今后研发 FCC催化剂的热点.     

EPOXIDATION OF FUNCTIONALIZED OLEFINS OVER SOLID CATALYSTS

Heterogeneous catalytic epoxidation of functionalized olefins in the liquid phase has been reviewed, focusing on catalyst performance and its interrelation with the crucial parameters of the catalytic systems. Efficient catalysts include supported and mixed oxides, framework-substituted (“redox”) molecular sieves, layered-type materials, heterogenized homogeneous catalysts, and some others. Among the various substrates, allylic and homoallylic alcohols, and unsaturated carbonyl compounds have received most attention so far. The great variety of available catalysts enables selective epoxidation of most substituted olefins. The mechanistic understanding of heterogeneous catalytic epoxidation is still underdeveloped, rendering catalyst design rather empirical. A considerable potential for future development lies in the area of “heterogenization” of successful homogeneous catalysts especially for asymmetric epoxidation. Crucial requirements in the development of heterogeneous catalytic epoxidation catalysts are, besides good catalytic performance and cheap oxidant, recyclability and resistance to leaching of the active component. Some of the examples shown in the literature do not fulfill the latter requirement.