不同硅铝比β分子筛的催化裂化性能对比

以大庆减压蜡油掺杂30%减压渣油为原料,在固定流化床评价装置上考察不同硅铝比的β分子筛助剂的催化裂化反应性能。结果表明,β分子筛硅铝比较小时,重油产率减小,轻油收率和总液体收率增加,气体（干气+液化气）产率减少,而汽油辛烷值增加,但过高硅铝比的β分子筛影响重油转化,适中硅铝比β分子筛助剂的反应性能较好。以中国石油天然气股份有限公司大连石化分公司四催化原料油为原料,在ACE装置上对比评价了直接合成与脱铝改性后获得的相近硅铝比的β分子筛助剂的催化裂化反应性能。结果表明,脱铝改性后获得的β分子筛的重油产率较低,轻油收率和总液体收率均有提高。     

Synergetic effects of Y-zeolite and amorphous silica-alumina as main FCC catalyst components on triisopropylbenzene cracking and coke formation

The synergetic effects of HY-zeolite and silica-alumina (SA), as two major components of an FCC catalyst, on the cracking activity and coking tendency during catalytic cracking of 1,3,5-triisopropylbenzene (TiPB, as a resid representative) were studied. NaY-zeolite and SA were synthesized by hydrothermal and co-precipitation methods, respectively, and ammonium exchanged for three times at 80 °C. The catalysts were characterized by XRD, XRF, SEM, BET, AAS and ammonia TPD techniques. TiPB cracking was investigated on four different catalyst configurations including SA, Y-zeolite, SA.Y and SA-Y in a fixed bed reactor. SA.Y stands for physical mixture of equal amounts of Y-zeolite and SA. For SA-Y, a bed of SA was placed upstream of the same amount of Y-zeolite. The catalysts were in-situ activated at 475 °C and evaluated by TiPB cracking at 350 °C. The coke content of the catalyst beds, after 40 min cracking of TiPB, was estimated by TPO using an FT-IR gas cell. At 3 min time on stream, 5.2 times higher yield of benzene, as a deep cracking product, is observed on SA-Y as compared to SA.Y. The TiPB conversion decreases in the order of SA-Y > SA.Y > Y-zeolite ? SA. Furthermore, as compared to Y-zeolite, 24% lower coke is formed on SA-Y. Also CO evolution during TPO of coked SA-Y catalyst is about 24% lower than that of the coked zeolite. As a result, protecting of Y-zeolite by SA from direct exposure to resid feed enhances the cracking activity, decreases the tendency to coke formation and diminishes CO emission in the catalyst regeneration process.     

Synthesis and catalytic cracking performance of mesoporous zeolite Y

Mesoporous zeolite Y (denoted as meso-Y) was synthesized using hydrothermal synthesis method using pluronic P123 block copolymer as template. Furthermore, stabilized Y (USY) was prepared through ion exchange and ultra-stabilization process of the meso-Y. The catalysts were prepared and characterized by XRD, SEM, TEM, N₂ adsorption–desorption, NH₃-TPD and Py-IR. These catalysts were evaluated by determining the micro-activity using the light diesel oil as sample. The results showed that the Meso-CAT-3 catalyst had the highest micro-activity and lowest coke yield. It could be ascribed to the mesoporous structure which is known to improve the mass transfer of the larger molecules.     

Catalytic reactions of n-hexenes on amorphous silica-alumina

Reactions of n-hexenes on 80/100 mesh amorphous silica-alumina have been studied in a plug flow reactor at 405°C, and compared with results previously obtained using HY and H-ZSM-5. The dominant primary reaction is skeletal isomerization while the initial selectivity for cracking is very low compared to that on the zeolite catalysts. The dimerization-cracking reaction, the major cracking process on the zeolites, was not a primary reaction on amorphous silica-alumina. This and the slowness of reactions leading to paraffins and dehydrogenated species is attributed to the small number of strongly acidic sites on the amorphous material.     

MCM-41分子筛加氢裂化催化剂的研究

按水热法合成出介孔MCM-41分子筛，在不同的气氛下焙烧脱除有机模板剂。在固定床流动反应器上，与USY分子筛对比了正庚烷加氢裂化结果，发现MCM-41分子筛有较好的抗氮中毒能力，且其稳定时的加氢裂解活性比USY分子筛高。     

Comparison of amorphous silica-alumina and highly dealuminated HY zeolite by1H high resolution MAS-NMR of solids

¹H MAS-NMR spectroscopy reveals analogies between partly dehydrated samples of silica-alumina and strongly dealuminated HY zeolite. There is a fundamental difference between the dehydration processes of crystalline and amorphous samples. A scheme for the reactions occurring during dehydration and dehydroxylation is proposed.     

薄片状Y型分子筛的合成及其裂化性能

采用导向剂法,以聚乙二醇-600（PEG-600）为形貌控制剂和分散剂,制备了具有薄片状形貌的小晶粒Y型分子筛。通过X射线衍射（XRD）、扫描电镜（SEM）、N₂吸附-脱附、吸附吡啶的原位红外和NH₃程序升温脱附（NH₃-TPD）技术对合成的Y型分子筛及制备的催化剂进行了表征。结果表明,所合成的Y型分子筛大部分呈薄片状形貌,相对于传统八面体形貌Y型分子筛来说,具有较高的外比表面积。1,3,5-三异丙基苯的催化裂化反应结果表明,与传统八面体形貌的Y型分子筛制备的催化剂相比,薄片状Y型分子筛具有较高的1,3,5-三异丙基苯裂化活性和裂化产物选择性。     

Five-lump kinetic model with selective catalyst deactivation for the prediction of the product selectivity in the fluid catalytic cracking process

The effective simulation of the fluid catalytic cracking (FCC) operation requires a good understanding of many factors such as, reaction kinetics, fluid dynamics, and feed and catalyst effects. The different product slates that can be obtained are the consequence of a complex reaction scheme including cracking, isomerization, hydrogen transfer, oligomerization, etc. Furthermore, the catalyst deactivation may affect each one of the reactions in different ways, which creates an additional reason for different variation with time-on-stream of the yield to each product. On the basis of the experimental data of the FCC pilot plant operated in Chemical Process Engineering Research Institute (CPERI, Thessaloniki, Greece), a lumping model was developed for the prediction of the FCC product distribution. The lumped reaction network involved five general lumps (gas oil, gasoline, coke, liquefied product gas, and dry gas) to simulate the cracking reactions and to predict the gas oil conversion and the product distribution. The paths of catalyst deactivation were studied and a selective deactivation model was adopted that enhances the fundamentality and accuracy of the lumping scheme. The hypothesis of selective catalyst deactivation was found to improve the product slates prediction. Models with different assumptions were examined, regarding the behavior of the catalyst, as deactivated, and its effect on the reactions of the lumping scheme. A large database of experiments, performed in the FCC pilot plant of CPERI was used to verify the performance of the models in steady state unit operation. The simulation results depict the importance of incorporating selective catalyst deactivation functions in FCC lumping models.     

催化裂化催化剂生产过程中分子筛粉碎技术的应用

在催化裂化催化剂生产过程中为了提高超稳分子筛的有效利用率,提升产品质量,使用了一系列超稳分子筛粉碎技术。对超稳分子筛聚集的原因及粉碎技术进行了对比分析,重点分析了介质超细研磨粉碎技术对催化剂质量指标的影响。造成超稳分子筛粒子聚集的主要原因是NaY分子筛合成过程中粒子间相互吸附,后续分子筛交换改性工序对分子筛粒度分布影响较小。介质超细研磨机和干磨粉碎技术对粉碎超稳分子筛效果明显,能够有效降低分子筛粒径,在催化裂化催化剂生产过程中介质超细研磨机的应用效果较好。经粉碎后的超稳分子筛能够明显降低催化裂化催化剂的磨损指数,提高微反活性。     

Zr改性Y分子筛中油型加氢裂化催化剂设计制备

采用等体积浸渍法对Y分子筛进行了Zr修饰改性,系统考察了不同用量Zr对改性Y分子筛的结构、催化剂的理化性质和加氢裂化反应性能的影响规律。通过XRD、NH₃-TPD、H₂-TPR和TEM等方法对改性分子筛和催化剂进行表征分析。结果表明：Zr改性降低了Y分子筛的酸量,随着改性Zr用量的增加,这种变化趋势不断增大。同时,Zr改性有效地削弱了分子筛催化剂中金属活性组分与载体间的作用,提高了W物种在催化剂表面的分散程度。加氢裂化反应结果表明：与Y分子筛催化剂相比,Zr改性Y分子筛催化剂的减压馏分油(VGO)转化率降低,中间馏分油选择性提高约20%,随着改性Zr用量的增加,VGO的转化率不断降低,中间馏分油选择性略有增加。     

The effect of pre‐coking on the activity and selectivity of the catalytic cracking of squalane

The pre‐coking of cracking catalysts has been reported to increase the yield of light cycle oil from fluid catalytic cracking. The present studies investigating an equilibrated catalyst show that this is not the case. The effect of pre‐treating equilibrated catalysts with coke and with ammonia shows that conversion was decreased in both cases and the product selectivity of the process changed. Both coke and ammonia were found to decrease site density, reducing the importance of hydrogen transfer reactions. Increased yields of light cycle oil as a result of pre‐coking can only be expected with fresh catalyst, where small amounts of coke deactivate the most acidic sites. Such sites have already been deactivated on equilibrated catalyst. Copyright © 2004 Society of Chemical Industry     

Cerium promoted and silica-alumina supported molybdenum oxide in the zeolite-containing hybrid catalyst for the selective deep catalytic cracking of petroleum naphthas

The high performance of hybrid catalysts in the selective deep catalytic cracking of n-hexane and n-heptane – used herein as model molecules for petroleum naphthas – is due to the pore continuum effect created by the close connection between the micropores of the acidified silicalite crystallites and the mesopores of the cocatalyst particles, located in fixed positions within a rigid matrix. The resulting enhanced conversion over the micro–meso hybrid catalyst is obtained regardless of the surface composition of the mesoporous cocatalyst or the molecular nature of the feed. However, it disappears when the two catalyst components are both mesoporous materials, i.e. in the case of a meso–meso hybrid catalyst. The main active component of the mesoporous cocatalyst, molybdenum oxide supported on silica–alumina, shows surface acidity of both nature (Bronsted and Lewis). Cerium oxide incorporated as dopant, has as main catalytic effect to increase the selectivity to light olefins, while the production of aromatics significantly decreases. However, when the ratio of [Ce]/[Mo] molar concentrations is higher than 0.8, theyield of product BTX aromatics rapidly increase at the expenses of that of light olefins. On the other hand, Ce loading onto the microporous silicalite or ZSM5 zeolite results in the same catalytic behavior as with the cerium-doped cocatalyst.     

Ethylene dimerization catalyst of nickel sulfate supported on silica-alumina

Catalysts containing various nickel sulfate content were prepared by dry impregnation of silica-alumina or silicagel with aqueous solution of nickel sulfate. SiO₂-Al₂O₃ alone without NiSO₄ was totally inactive for the ethylene dimerization reaction at room temperature. However, NiSO₄/SiO₂-Al₂O₃ was found to be very active even at room temperature compared with NiSO₄/SiO₂.     

Rhodium supported in basic zeolite Y: A selective and stable catalyst for CO hydrogenation

Catalysts prepared by a condensation reaction of Rh(CO)₂(acac) within the supercages of zeolite Y made basic by treatment with NaN₃ are active for CO hydrogenation and selective for low-molecular-weight olefins and methanol. High partial pressures of CO (or CO + H₂) stabilize the catalyst. The predominant species in the catalyst are suggested to be rhodium carbonyl clusters trapped in the zeolite cages.     

Comments on the use of buckminsterfullerene encapsulated in zeolite Y as a potential catalyst

Buckminsterfullerene encapsulated within zeolite Y is found not to be a reactive radical initiator for the formation of dimethoxyethane from dimethyl ether below 200° C. Above this temperature the expected acid catalysed conversion of dimethyl ether to hydrocarbons is observed. Dimethoxyethane formation is observed when bibenzoyl peroxide is used as a radical initiator. These studies indicate that any radical formed by the encapsulated buckminsterfullerene is relatively unreactive.     

Immobilized iron Schiff base histidine complexes on Al-MCM-41 and zeolite Y as catalyst for oxidation of cycloalkanes

Iron complexes of N-salicylidene-l-histidine with or without bipyridine ligand immobilized on Al-MCM-41 and zeolite Y designated as Fe(sal-l-his)(bipy)complex/Al-MCM-41 or Fe(sal-l-his)complex/Al-MCM-41 and Fe(sal-l-his)(bpy)complex/Y or Fe(sal-l-his)complex/Y respectively, were prepared and characterized by X-ray powder diffraction (XRD), FT-IR, N₂ adsorption/desorption and chemical analysis techniques. Fe(sal-l-his)/Al-MCM-41 and Fe(sal-l-his)(bipy)complex/Al-MCM-41 were found to successfully catalyze the oxidation of cyclohexane, methyl cyclohexane, cyclooctane and adamantane with H₂O₂. The oxidation results and promising catalytic behavior of Fe(sal-l-his)(bipy)complex/Al-MCM-41 for oxidation of cyclooctane with 90 % conversion and excellent selectivity toward the formation of cyclooctanone will be discussed in this presentation.     

Effect of temperature on the product selectivity and aromatics distribution in aromatization of propane over H-GaAlMFI zeolite

The influence of temperature on the product selectivity, aromatics distribution, p-X/o-X and p-X/m-X product ratios, aromatization/cracking and aromatization/dehydrogenation ratios have been exhaustively investigated on H-GaAlMFI at different iso-conversions of propane. These studies show a profound influence of temperature on the product selectivity/distribution of the propane aromatization reaction. The aromatization activity of the H-GaAlMFI zeolite decreases at higher temperatures relative to the cracking and dehydrogenation activities. The benzene selectivity increases whereas the toluene and C₈ selectivity decreases with increasing reaction temperature. The product selectivity and the formation of xylene isomers are kinetically controlled.     

The effect of exchanged cations and heat treatment on the adsorption of carbon monoxide,nitrogen, argon,and krypton on amorphous silica-alumina cracking catalysts

Adsorption isotherms for CO, N₂, Ar, and Kr were measured over the temperature range ?50–250 °C over a pressure range of 2–350 Torr on exchanged and unexchanged silica-alumina cracking catalysts that had been evacuated at 250, 450, and 800 °C, respectively. Isosteric heats of adsorption were calculated at surface coverages ranging from 0.1 to 1%.When the samples were evacuated at 250 °C, the adsorption of CO was increased by a factor of about 3.5 when the exchanged cations were Ca and Ba and about 50% for K cations and also for ions of La and Mg. The influence of cations became even greater when the samples were evacuated at 450 °C, the adsorption for the samples exchanged with cations being three times as great on specimens evacuated at 450 °C as for samples evacuated at 250 °C. Evacuation of samples at 800 °C caused the adsorption of CO on the H form of the sample to be substantially the same as for the ones exchanged with calcium ions. The isotherm for the Ca exchanged specimen was substantially the same as for the sample evacuated at 450 °C.Isosteric heats of adsorption in general were highest for La and Ca exchanged samples, somewhat lower for those exchanged with K and least for those containing protons on the exchange sites. However the heats of adsorption on samples evacuated at 800 °C approached 15 kcal/mole of CO both for samples exchanged with Ca ions and for the protonic samples. Corresponding heats of adsorption of nitrogen were in the range of 7–9 kcal/mole of N₂. Heats of adsorption of argon and krypton remained down in the range of 2.5–3.5 kcal/mole for all samples, and were not much influenced by the temperature of evacuation or the exchange of ions on the catalyst surface. The molecules for which the big changes in adsorption with temperature of evacuation and ion exchange of samples were noted were carbon monoxide and nitrogen, both of which have rather high quadrupole moments.     

Isobutane/2-butene alkylation on MCM-22 catalyst. Influence of zeolite structure and acidity on activity and selectivity

The catalytic behavior of the novel MCM-22 zeolite for the continuous alkylation of isobutane with 2-butene has been investigated at a temperature of 50°C, 2.5 MPa total pressure, and a variety of olefin space velocities. At high olefin conversions the MCM-22 zeolite showed a very high initial cracking activity attributable to strong Brønsted acid sites, as well as to the existence of strong diffusional restrictions of the TMP's (formed inside the zeolite) to exit through the channels. At short times on stream (TOS), TMP's account for ca. 40% of the C₈ fraction. The olefin conversion and the cracking activity rapidly decline with TOS, while the alkylate product became richer in dimethylhexenes, indicating a predominance of 2-butene dimerization and a loss of hydrogen transfer activity as the catalyst aged. Moreover, MCM-22 gives less TMP's than large-pore zeolites (USY, beta, mordenite), but more than the mediumpore ZSM-5 at similar 2-butene conversion. The latter catalyst was much more selective for olefin dimerization than for isobutane alkylation, presumably because formation of the bulkier TMP's was strongly impeded in its smaller pores.     

Nafion-H as catalyst for isobutane/2-butene alkylation compared with a cerium exchanged Y zeolite

A solid superacidic Nafion-H polymer was examined as a catalyst for isobutane/2-butene alkylation and compared with a cerium-exchanged Y zeolite. Both catalysts demonstrate initial alkylation activity with rapid decrease in alkylation selectivity. The total product distributions were found to be significantly different after three hours of reaction. Nafion-H showed less selectivity towards iso-octanes, but formed relatively more 2,2,4-trimethylpentane. The differences between the two catalysts suggest dissimilar favoured reaction mechanisms.