OPTIMAL DISTRIBUTION OF MULTIFUNCTIONAL CATALYSTS IN A PACKED BED REACTOR

The problem of the optimal distribution of two multifunctional catalysts is analyzed. Two methods for obtaining optimal catalyst profiles, an analytic-numeric method and the method of steepest ascent, are compared. Though the analytic-numeric method yields a more accurate solution, the method of steepest ascent is usually easier to apply. Optimal catalyst loading profiles are determined for two cases of commercial interest: selective oxidation of butene and naphtha reforming with bimetallic catalysts- A sequential loading of the bismuth molybdate and the vanadium phosphate catalysis is recommended for low butene concentration levels, while at higher butene levels a mixed loading of the two catalysts may be desirable. For commonly encountered naphtha feedstocks a sequential loading of the Pt-Re and the Pt-Ir catalysts tends to be optimal. These compare well with experimental evidence in the literature.     

OPTIMAL CATALYST DISTRIBUTION AND DILUTION IN NONISOTHERMAL PACKED BED REACTORS

The problem of the optimal distribution of two different catalysts in a nonisothermal packed bed reactor is analyzed. State variable constraints, such as maximum allowable temperature, may be incorporated through a penalty function approach into the steepest ascent solution of this problem.

Loading a wall-cooled reactor with two chemically different catalysts is compared to dilution of a single catalyst with inerts for temperature moderation. A criterion is presented for estimating whether catalyst dilution may be necessary in order to keep reactor temperature below some maximum allowable value.

Conditions for optimal loading with a two-dimensional reactor model are presented and applied to catalyst dilution in a butane oxidation reactor. Suboptimal catalyst loadings are compared with the optimal loading.     

Catalytic cracking of 1-butene to propylene by Ag modified HZSM-5

Silver modified HZSM-5 (AgHZ) zeolite catalysts were prepared by ion exchange method and their catalytic properties in the 1-butene cracking reaction were measured. The catalysts were characterized by infrared spec-troscopy with pyridine adsorption (Py-IR), N2 adsorption and X-ray diffraction (XRD). The effects of Ag loading and steaming treatment on catalytic performances were studied. It is found that the activity of HZSM-5 (HZ) cat-alyst significantly decreases with the steaming time, whereas AgHZ catalysts show stable activity in the steaming time of 24–48 h and their activities increase with the Ag loading. When the steaming time is 24–48 h, the yield of propylene over HZ catalyst significantly decreases, whereas it is stable over AgHZ catalysts. The AgHZ catalysts with Ag loadings of 0.28%–0.43%(by mass) show similar propylene yields (~30%), which are higher than that over the AgHZ catalyst with a Ag loading of 0.55%(by mass). These results indicate that the steam-treated AgHZ catalysts with optimum Ag loadings have higher yield of propylene and are more stable than the steam-treated HZ catalyst. The regeneration stability measurement in butene cracking also shows that the AgHZ catalyst steam-treated under a suitable condition has better stability than the HZ catalyst.     

催化轻汽油醚化催化剂催化性能评价

在200 mL固定床反应器上对催化轻汽油醚化催化剂催化性能进行了考察。对比了1#、2#两种催化剂在不同温度下对催化轻汽油的醚化效果。试验结果表明,两种催化剂均表现出了良好的催化性能,且具有较高的活性和稳定性。催化轻汽油醚化前总烯烃含量为42.33%,1#催化剂醚化后总烯烃含量可降至26.35%,2#催化剂醚化后总烯烃含量可降至24.67%。理论计算表明,两种催化剂条件下,轻汽油辛烷值均可提高约3个单位。     

Analysis of kinetic data accompanied by catalyst fouling with application to olefin hydrogenation

Measurements of kinetic data in experimental catalytic reactors are often plagued by non-constant catalytic activities, for example, due to unexpected fouling of catalysts, even during a relatively short time interval. The purpose of the present work is to illustrate how the data analysis in the composition space can be conveniently employed to derive appropriate kinetic information from such ill-defined rate data. The catalytic reaction considered is the hydrogenation of propene, butene, and their mixtures at 3.5 MPa over a presulfided Co-Mo catalyst supported on gamma-alumina, in which volatile polymer formation of butene at low reaction temperatures and depolymerization at higher temperatures are observed to occur. The present work reports the data analysis methods employed, which eventually have led to consistent reaction pathways and to the determination of relative rate constants associated with them. The results reported herein may be useful for designing and operating commercial hydrotreaters where various C₃/C₄ olefin mixtures are hydrogenated. The methodology adopted here may be extended to any complex reaction system such as catalytic reforming of naphtha.     

Deactivation behavior of the catalyst in solid acid catalyzed alkylation: effect of pore mouth plugging

The deactivation of solid acid catalysts in liquid-phase alkylation of isobutane with butenes was investigated. The role of pore mouth plugging, in particular, was studied and it was found that it had a significant effect on the deactivation behavior. Simple explicit correlations were developed for catalyst lifetime in a CSTR, both in terms of time-on-stream and butene turnover per catalyst weight. The correlations were tested using available experimental data from the literature and a reasonable agreement was observed. It was shown that for a zeolitic catalyst the butene turnover per catalyst weight was proportional to the square root of catalyst loading, while it was inversely proportional to both the olefin feed concentration and the square root of feed flow rate.     

Naphtha derived from polyolefins

Conversion of polyolefins (HDPE, LDPE and PP) into feedstock naphtha was investigated by hydroliquefaction process. Hydroliquefaction experiments were carried out under cold hydrogen pressure of 5 MPa at the temperatures between 375 and 450 °C in absence and presence of catalyst. Two types commercial catalysts were used, a hydrocracking catalyst (DHC-8) and a hydrogenation catalyst (HYDROBON). The effect of temperature and catalyst type on product yields and composition of gas and liquid products was investigated. The temperature was the main effect in hydroliquefaction. DHC-8 showed good cracking activity, but it gave the liquid product containing high olefin content same as thermal run. Although HYDROBON catalyst produced the sufficient amount of liquid (and naphtha fraction) at the higher temperature, it gave the liquid product with very low olefin content. The naphtha fractions obtained from polyolefins under the optimal hydrocracking conditions were analyzed by PIONA instrument to determine the hydrocarbon groups. PIONA analysis showed that the naphtha obtained from hydroliquefaction over HYDROBON catalyst could be used as a petrochemical feedstock. However, the naphtha obtained in presence of DHC-8 catalyst, which is to be used a feedstock, was needed further hydrogenation treatment.     

Butene Catalytic Cracking to Propene and Ethene over Potassium Modified ZSM-5 Catalysts

Catalytic cracking of butene over potassium modified ZSM-5 catalysts was carried out in a fixed-bed microreactor. By increasing the K loading on the ZSM-5, butene conversion and ethene selectivity decreased almost linearly, while propene selectivity increased first, then passed through a maximum (about 50% selectivity) with the addition of ca. 0.7–1.0% K, and then decreased slowly with further increasing of the K loading. The reaction conditions were 620 °C, WHSV 3.5 h⁻¹, 0.1 MPa 1-butene partial pressure and 1 h of time on stream. Both by potassium modification of the ZSM-5 zeolite and by N₂ addition in the butene feed could enhance the selectivity towards propene effectively, but the catalyst stability did not show any improvement. On the other hand, addition of water to the butene feed could not only increase the butene conversion, but also improve the stability of the 0.7%K/ZSM-5 catalyst due to the effective removal of the coke formed, as demonstrated by the TPO spectra. XRD results indicated that the ZSM-5 structure of the 0.07% K/ZSM-5 catalyst was not destroyed even under this serious condition of adding water at 620 °C.     

异丁烷/丁烯烷基化分子筛催化剂的失活研究进展

分子筛催化剂在催化异丁烷/丁烯烷基化中具有良好的应用前景,但易失活,需频繁再生。系统总结分子筛催化剂在异丁烷/丁烯烷基化反应中的研究进展,认为烯烃低聚物覆盖活性位、堵塞分子筛孔道是催化剂失活的直接原因。论述了分子筛性能及烷基化反应条件对分子筛失活的影响,指出具有合适B酸强度和数量、易于丁烯低聚物脱附、利于扩散的分子筛催化剂是未来的研究方向。     

铁酸盐系列丁烯氧化脱氢催化剂研究进展

综述了铁酸盐系列催化剂(Fe系催化剂)在丁烯氧化脱氢反应中的应用研究进展,介绍了Fe系催化剂的活性中心和氧化脱氢机理,分析了催化剂的失活原因,详述了助剂对Fe系催化剂催化性能的影响,并对Fe系催化剂的发展方向进行了展望。开发出高反应活性、高选择性和高强度的新一代Fe系丁烯氧化脱氢制丁二烯的高效催化剂,是今后的主要研究方向,同时,开发资源利用率高、低投资、低生产成本和废水量少的丁烯氧化脱氢工艺也非常关键。     

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。     

Optimal catalyst profiles for a two-step reaction sequence in a packed bed

Optimal catalyst profiles have been determined for a two-step reaction sequence, where each step is catalyzed by a separate substance, for two cases: one where the remaining amount of initial reactants is minimized, and the second where the concentration of final product is maximized. The effect of varying levels of intraparticle diffusion, initial reactant concentration, residence time, and catalyst loading was investigated. It was found that increasing conversion led to a greater duration of intermediate control, where both catalysts are present in proportions that varied with reactor length. At no point during intermediate control, however, did the catalyst for the initial reaction increase in concentration with increasing length.     

丁烯齐聚酸性催化剂的研究进展

介绍了丁烯在酸性催化剂上齐聚的反应机理,并以固体磷酸催化剂、分子筛催化剂、负载型催化剂和酸性树脂催化剂为线索,评述了国内、外用于丁烯齐聚反应的酸性催化剂的研究进展。     

重整切尾油催化加氢生产优质溶剂油

介绍了中国石油抚顺石化公司石油三厂以重整切尾油为原料,通过加氢微型试验装置,筛选出加氢精制催化剂3996与加氢脱芳催化剂FV-1,将上述2种催化剂按照体积比1︰1进行组合装填,在加氢微型试验装置进行一段加氢法生产塑胶溶剂油试验,并经过了工业生产运行。结果表明,在适宜的操作条件下,可以出合格的塑胶油产品,并获得较好的经济效益。     

器外预硫化型加氢催化剂的制备与性能研究

以Ni和Mo为活性组分,Al2O3为载体,制备了氧化型Ni-Mo/Al2O3催化剂O-1,在此基础上,以自制的水溶性复合硫化物为硫化剂,制备了器外预硫化型Ni-Mo/Al2O3催化剂S-1,通过BET、XRD和HRTEM等手段对2种催化剂的物化性质做了表征,并对比考察了催化剂对劣质石脑油加氢脱硫脱氮的性能。结果表明：器外预硫化型催化剂对劣质石脑油加氢脱硫脱氮的性能与氧化型催化剂接近,其加氢石脑油产品的硫氮含量均低于0.5 μg/g,这说明采用水溶性复合硫化物为硫化剂可以对氧化型催化剂进行有效地器外预硫化。     

Effect of process variables on product yield distribution in thermal catalytic cracking of naphtha to light olefins over Fe/HZSM-5

The effect of temperature, WHSV and Fe loading over HZSM-5 catalyst in thermal-catalytic cracking (TCC) of naphtha for the production of light olefins has been studied. The response surface defined by three most significant parameters is obtained from Box-Behnken design method and the optimal parameter set is found. The results show that ethylene increases with temperature, while propylene shows an optimum at 650 °C. Moderate WHSV is favorable for maximum production of light olefins. Addition of Fe to HZSM-5 has a favorable effect on the production of light olefins up to 6% of loading. Excess amount of loading decreases the conversion of naphtha, which leads to a drop in light olefin yields. The yield of light olefins (ethylene and propylene) at 670 °C, 44 hr⁻¹ and 6 wt% Fe has been increased to 5.43 wt% compared to the unmodified HZSM-5 and reaches to 42.47 wt%.     

活性炭负载磷钨酸催化合成烷基多苷

用活性炭负载磷钨酸为催化剂,用二步法合成了十二烷基多苷(APG)。丁苷化反应的最优工艺条件是:磷钨酸负载量20%,用量为葡萄糖的5%,n(葡萄糖)∶n(丁醇)为5∶1,温度120℃,反应时间2 h。催化剂可以重复使用。在n(十二醇)∶n(葡萄糖)为2.5∶1时,可以用水萃取分离APG,得到的产品色浅且稳定。APG在水溶液中的临界胶束浓度为65.5 mg/L,表面张力为25.2 mN/m,泡沫力为160 mm,5 min后泡沫高度为158 mm。     

改性铁酸锌催化剂的合成及其丁烯氧化脱氢活性

采用共沉淀法制备铁酸锌催化剂,考察改性元素Mg、B、Zr、Ce、La对铁酸锌催化剂结构和丁烯氧化脱氢性能的影响。采用XRD、TEM和N_2吸附-脱附对镧改性铁酸盐催化剂进行金属元素组成的优化研究,确认镧元素在催化剂中存在的形态和作用。结果表明,La改性铁酸锌催化剂晶粒粒径(20～50) nm,具有较大的比表面,主要活性组分是α-Fe_2O_3和ZnFe_2O_(4,)催化剂的活性随着Fe含量的升高而升高,n(Fe)∶n(Zn)∶n(La)=4∶1∶1催化剂具有最高的催化活性,反应温度380℃时,其TOF值2.1×10~(-3) mol_(butene)·mol_(surface-Fe)·s~(-1)。     

丁烯法合成醋酸仲丁酯催化剂及生产工艺探讨

筛选适合丁烯法合成醋酸仲丁酯反应的树脂催化剂,确定适合醋酸仲丁酯反应的工艺条件,介绍工业装置中不同工艺的差别和A、B、C三套工业装置的实际运行情况,指出醋酸仲丁酯行业的发展方向。结果表明,采用丹东明珠特种树脂有限公司生产的大孔磺酸型树脂A为催化剂,较佳的工艺条件为:空速1.0 h~(-1),压力1.5 MPa,酸烯物质的量比2∶1~3∶1,反应温度(70~90)℃。工业装置运行数据表明,在反应器数量相同、催化剂装填量和丁烯组成基本相似情况下,使用两种不同树脂催化剂,反应初期的反应温度降低,丁烯总转化率提高。使用两种不同树脂催化剂有利于降低装置能耗和提高单位产品产量。     

异丁烷/丁烯烷基化固体酸催化剂的再生方法研究进展

阐述了固体酸烷基化催化剂在异丁烷/丁烯烷基化中的再生方法研究进展,包括金属临氢再生、氧化煅烧再生、超临界流体再生、洗涤再生,同时对固体酸烷基化催化剂的失活原因和失活形式进行了分析评述。这些方法在一定条件下可以实现催化剂不同程度的再生,但由于操作以及成本等原因都停留在实验室阶段,本文综合比较了各种再生方法的再生工艺过程以及再生效果,分析各种再生方法的优劣。固体酸烷基化催化剂失活较快是阻碍异丁烷/丁烯固体酸烷基化工艺工业化的关键因素,研究探索操作简单、成本低、有效的固体酸烷基化催化剂再生方法仍将是今后该领域的研究热点。