碳五烃催化裂解制取低碳烯烃反应性能及机理

以ZSM-5分子筛为催化剂,碳五烃混合物为裂解原料,考察温度及稀释比对碳五烃催化裂解制丙烯/乙烯反应性能的影响。结果表明:随温度升高碳五烷烃及烯烃的转化率均不断升高,但碳五烯烃的转化率远高于碳五烷烃的转化率。同时乙烯及丙烯的收率也随温度的升高而升高,空速3.06 h-1,分压23.24 k Pa时,分别由450℃的2.38%,8.84%升高到620℃时的13.86%和19.67%。另外,随稀释比的增加,碳五烯烃转化率,乙烯、丙烯及丁烯的收率不断下降,但C6烃的收率随稀释比的增加而升高。碳五烯烃催化裂解机理分析指出:碳五烯烃催化裂解过程中碳五烯烃在直接裂解生成乙烯和丙烯的同时,也可通过二聚成C10中间体,然后生成的C10中间体再发生顺次裂解反应。该机理应用于实验规律的解释,取得了满意的结果。     

C_4烯烃制丙烯催化剂

用超细氧化硅为载体、高硅铝比的ZSM-5分子筛为活性组分,挤条成型制成催化剂。用氧化钙和氧化硼的前体化合物改性,在580℃、常压、水质量空速为1h-1的条件下进行预处理24h,在500℃、0.1MPa、水/C4质量比为0.2、C4质量空速为3h-1的条件下,C4烯烃制丙烯和乙烯的反应产物组成稳定,在连续25天的反应过程中,C4烯烃转化率大于68%,丙烯收率大于30%,乙烯收率大于6%,催化剂的积炭量为6.2%。对成型、改性、水蒸气预处理和再生后的催化剂用BET、NH3-TPD和Py-IR进行表征,分析催化剂活性与酸性的关系,认为催化剂表面质子酸(B酸)与催化剂的活性有关。     

SAPO-34催化剂上C4烯烃催化裂解与甲醇转化制烯烃反应耦合

采用SAPO-34催化剂,在流化床装置上考察了甲醇制烯烃(MTO)副产C4烯烃催化裂解制乙烯和丙烯的反应行为,分析了C4烯烃转化率、产物收率等主要指标随工艺参数的变化规律,对比了C4烯烃催化裂解和MTO反应积炭催化剂的差异,提出了C4烯烃催化裂解适宜的关键工艺条件。C4烯烃催化裂解对比MTO反应需要较高的反应温度和催化剂活性。结果表明,C4烯烃裂解反应过程形成的积炭催化剂仍可用于MTO反应,并且具有较高的甲醇转化率和低碳烯烃选择性,因此可以采用SAPO-34催化剂把两个独立的反应串联耦合在一起。     

C4和C5回炼对提高甲醇制烯烃(MTO)收率的研究

甲醇制烯烃(MTO)装置使用的催化剂SAPO-34分子筛具有较强的酸性催化特征,利用该性质对C_4和C_5进行裂解实验,文中通过实验得出在甲醇制烯烃催化剂的作用下能够部分裂解C_4和C_5,裂解产物中有目的产物质量分数约25%,不同的再生定碳对C_4和C_5的裂解程度也有差异,当再生催化剂定碳控制在1.3%—1.6%时,C_4和C_5的裂解程度最优。C_5回炼时,乙烯和丙烯的收率能提高0.49%;同时,未反应的C_4/C_5进入反应器后抑制了甲醇制烯烃反应中C_4/C_5的生成,进一步提高烯烃的收率。     

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。     

石脑油催化裂解制低碳烯烃动力学

根据石脑油催化裂解的反应体系和集总理论,建立6集总动力学模型,采用Levenberg-Marquardt算法求解ZSM-5分子筛催化剂作用下的石脑油催化裂解动力学参数。结果表明,丙烯收率大大高于乙烯收率,丙烯与乙烯的质量比为1.0～2.0,明显高于传统的石脑油水蒸气裂解工艺,各集总的反应活化能均大于100 kJ/mol。通过对模型进行检验,发现模型计算值与实验值之间的误差均小于15%,表明该动力学模型能较好地预测石脑油催化裂解制低碳烯烃反应。     

反应温度对催化裂化汽油芳构化的研究

以中国石油兰州炼油石化公司催化汽油为原料,采用小型固定流化床为芳构化反应装置,考察了反应温度对芳构化产物收率、转化率、马达法和研究法辛烷值、气体产品组成和液体产品组成的影响规律。实验结果表明,随着反应温度的升高,干气、液化气和焦炭收率呈上升趋势,而汽油和柴油收率呈下降趋势,FCC汽油的转化率都在94%左右,且随反应温度的升高先增大后减小;乙烯、丙烯、丁烯、乙烯和总低碳烯烃收率单调增加,而乙烯、丙烯、丁烯、乙烯和丙烯和总低碳烯烃收率的增加幅度各不相同;异构烷烃和烯烃收率随着反应温度的升高逐渐减少,而芳烃的收率和选择性随着反应温度的升高逐渐增加,正构烷烃和环烷烃的收率随着温度的增加先增加后减少。     

1-丁烯催化裂解制丙烯和乙烯反应性能的研究

以MCM-49分子筛为催化剂,纯1-丁烯为原料,考察了反应温度对烯烃催化裂解制丙烯、乙烯反应性能的影响。选择适宜的反应温度条件能够有效地抑制副反应,从而提高丙烯、乙烯的总产率。     

碳四烯烃制丙烯催化剂及其工业应用

研究碳四烯烃催化裂解制丙烯BOC-1催化剂的放大制备及其工业应用,详细介绍催化剂放大制备后实验室小试和工业应用评价结果。BOC-1催化剂在工业生产装置中运行和再生性能良好,丙烯单程收率28.5%,碳四烯烃转化率82.1%,催化剂使用周期17天,各项性能指标均超过洛阳炼化宏力化工有限责任公司的工业催化剂水平,适合进一步推广使用。建立由烯烃催化裂解、吸收稳定、气分、MTBE醚化和烷烃分离5个单元组成的碳四烯烃资源综合利用工艺流程,并使用VMGSim流程模拟软件进行模拟计算。结果表明,采用新工艺流程,碳四烯烃综合利用率99.3%,聚合级丙烯收率35.19%。     

MTO工业装置增产乙烯和丙烯的措施

为了获得较高的乙烯和丙烯选择性和收率,通过对甲醇制烯烃工业装置中乙烯和丙烯选择性和收率的影响因素进行分析,得到优化控制指标。反应温度490℃,反应压力~0.109MPa,催化剂定碳~5.9%,催化剂的停留时间一般为40~50分钟,原料甲醇空速一般为4.5~6 h-1,再生温度至少为650℃,可以获得较高的乙烯+丙烯组分。     

DMTO再生催化剂经C4/C5+裂解预积炭后对MTO反应性能的影响

采用小型固定流化床,研究了MTO副产物C4/C5^+烯烃在DMTO再生催化剂上的催化裂解反应、预积炭情况,以及预积炭后再生催化剂对MTO反应性能的影响。结果表明:C4/C5^+烯烃可作为原料在DMTO再生催化剂上进行催化裂解,生成乙烯、丙烯,增加双烯产量。在此裂解过程中,DMTO再生催化剂发生预积炭,可以提高MTO反应中双烯的初始选择性,缩短反应诱导期,提高双烯收率;同时,可以减小甲醇的生焦率,降低甲醇消耗。DMTO再生催化剂预积炭会影响催化剂寿命,其经C4/C5^+裂解预积炭过程中碳质量分数以3%左右为宜。     

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。     

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.     

Enhancing the Production of Light Olefins by Catalytic Cracking of FCC Naphtha over Mesoporous ZSM-5 Catalyst

The enhanced production of light olefins from the catalytic cracking of FCC naphtha was investigated over a mesoporous ZSM-5 (Meso-Z) catalyst. The effects of acidity and pore structure on conversion, yields and selectivity to light olefins were studied in microactivity test (MAT) unit at 600 °C and different catalyst-to-naphtha (C/N) ratios. The catalytic performance of Meso-Z catalyst was compared with three conventional ZSM-5 catalysts having different SiO₂/Al₂O₃ (Si/Al) ratios of 22 (Z-22), 27 (Z-27) and 150 (Z-150). The yields of propylene (16 wt%) and ethylene (10 wt%) were significantly higher for Meso-Z compared with the conventional ZSM-5 catalysts. Almost 90% of the olefins in the FCC naphtha feed were converted to lighter olefins, mostly propylene. The aromatics fraction in cracked naphtha almost doubled in all catalysts indicating some level of aromatization activity. The enhanced production of light olefins for Meso-Z is attributed to its small crystals that suppressed secondary and hydrogen transfer reactions and to its mesopores that offered easier transport and access to active sites.     

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。     

流化催化裂化汽油改质和增产低碳烯烃的研究

采用GL型催化剂,在小型固定流化床实验装置上考察了反应温度、剂油比、空速和水油比等操作条件对流化催化裂化(FCC)汽油催化改质汽油的产品分布、低碳烯烃(丁烯、丙烯和乙烯)产率和族组成的影响。实验结果表明,在一定反应条件下,FCC汽油通过催化改质可以降低烯烃含量,提高芳烃含量和辛烷值,在满足新汽油标准的同时提高了低碳烯烃的产率。此外,较高的反应温度、剂油比和水油比以及较低的空速有利于FCC汽油催化改质和增产低碳烯烃。     

Catalytic production of olefins using natural halloysite nanotubes

The production of C₂-C₄ olefins by deep catalytic cracking and the thermocontact pyrolysis of vacuum gas oil, commercial-grade cottonseed oil, and a vacuum gas oil-cottonseed oil 90: 10 mixture in the temperature range of 600–800°C is studied using natural halloysite extracted from kaolinite fields in the form of aluminosilicate sheets rolled in nanotubes. It is found that in the deep catalytic cracking of vacuum gas oil at 600°C using halloysite as a catalyst, the gain in the yield of ethylene is 6.4–10.1 wt %, compared to yields of this product when using ZSM-5 catalyst. Adding 10% commercial-grade cottonseed oil to the vacuum gas oil further increases the yield of ethylene by 2.2 wt % with a simultaneous 3.3 wt % rise in the yield of propylene. The cracking of pure cottonseed oil under identical conditions yields ethylene and propylene of 16.1 and 9.2 wt %, respectively. The possibility of using halloysite nanotubes as a heating surface for the thermal pyrolysis of the above feedstocks at temperatures of 700–800°C in order to obtain yields of C₂-C₃ olefins exceeding those of identical products in industry, and of reusing halloysites in the thermoconversion of the studied feedstocks via their complete regeneration, is confirmed.     

正己烷在HZSM-5分子筛上的催化裂解研究

为筛选反应活性和烯烃选择性相对较高的催化剂用于研究吸热型碳氢燃料的催化裂解,以正己烷的催化裂解作为探针反应,探讨其在不同硅铝物质的量比HZSM-5［n(Si)∶n(Al)=25、36、100］分子筛上催化裂解的反应活性和产物分布。结果表明,正己烷在HZSM-5分子筛上的裂解转化率随温度的升高和分子筛中硅铝物质的量比的减小而增大;裂解产物中乙烯、丙烯和总烯烃的选择性均随裂解温度的升高和分子筛中硅铝物质的量比的增加而增加,在（300~550） ℃,HZSM-5［n（Si)∶n(Al)=36］上的总烯烃收率最高,芳烃含量随分子筛中硅铝物质的量比的增加而减小;基于裂解转化率、烯烃和芳烃收率等因素综合考虑,HZSM-5 n(Si)∶n(Al)=36］分子筛为优选催化剂。     

Study on reformulation of fluid catalytic cracking gasoline and increasing production of light olefins

The effects of reaction temperature, mass ratio of catalyst to oil, space velocity, and mass ratio of water to oil on the product distribution, the yields of light olefins (light olefins including ethylene, propylene and butylene) and the composition of the fluid catalytic cracking (FCC) gasoline upgraded over the self-made catalyst GL in a confined fluidized bed reactor were investigated. The experimental results showed that FCC gasoline was obviously reformulated under appropriate reaction conditions. The olefins (olefins with C atom number above 4) content of FCC gasoline was markedly reduced, and the aromatics content and octane number were increased. The upgraded gasoline met the new standard of gasoline, and meanwhile, higher yields of light olefins were obtained. Furthermore, higher reaction temperature, higher mass ratio of catalyst to oil, higher mass ratio of water to oil, and lower space velocity were found to be beneficial to FCC gasoline reformulation and light olefins production.     

Controllably tailoring external surface sites of nanosheet HZSM-5 for maximizing light olefins in catalytic cracking of n-decane

A series of triphenylethoxysilane (TPEOS)-modified nanosheet HZSM-5 catalysts (ZN-x,x =4％,8％ and 16％,mass) were synthesized by chemical liquid deposition to selectively change external acidity distri-butions.TPEOS modification was found to passivate some external Brφnsted and Lewis acid sites by 37.8％,in which Brφnsted acid sites (BAS) were found more easily sacrificed by breaking the surface Al-O bond of bridging hydroxyl groups and forming Si-O-Si bonds.The selectivity of ZN-8 catalyst for light olefins (ethylene,propylene and butene) in n-decane catalytic cracking is up to 26％ (450 ℃,WHSV =10.95 h-1),which is ca.78％ higher than that of parent one.The better performance was attrib-uted to the appropriate external acid density in ZN-8,which inhibits bimolecular hydrogen transfer reac-tion of light olefins on the adjacent acid sites,resulting in more olefins,few coke precursors and thus an excellent catalytic stability.