催化剂制备中的磨损强度及其对催化性能的影响

催化裂化（FCC）催化剂制备装置的催化剂损耗主要取决于催化剂的粒度分布、磨细粉量和沸石催化剂的活性稳定性。考察了不同工艺制备的催化剂耐磨性能和反应性能的差异。     

不同高岭土系黏土性质及在催化裂化催化剂中的应用

随着原料油重质化、劣质化程度逐渐增高,催化裂化催化剂基质不仅需要保证催化剂有良好的磨损性能和流化性能,还需要具有适当的孔和一定的酸性对原料油中的大分子进行预裂化。半合成催化裂化催化剂中的高岭土系黏土对催化剂性能有重要影响。高岭土可直接或经酸、碱改性作为催化剂基质,也可通过原位晶化技术合成分子筛或含有Y型分子筛的催化剂。累托石通过交联反应可以合成层柱分子筛用于催化裂化催化剂制备。埃洛石因其管状结构,作为基质时催化剂具有孔体积和比表面积大及活性高的特点。对催化裂化催化剂中高岭土系黏土结构、改性方法及在催化裂化催化剂中应用进行综述,并对今后高岭土在催化裂化催化剂中的研究方向进行展望。     

由煤系高岭土合成小晶粒NaY分子筛及其应用

利用不同的方法分别合成了常规尺寸和纳米NaY分子筛,并采用XRD和TEM手段对合成样品进行了表征,小晶粒分子筛其粒径小于100 nm。催化裂化试验表明,纳米分子筛可提高大分子转化能力及改善产物选择性,比常规晶粒尺寸分子筛更为优越的性能。     

Preparation and Properties of Fluid Cracking Catalysts for Residual Oil Conversion

Catalytic cracking of petroleum to produce gasoline began in about 1912. The early pioneering work was carried out by Eugene Houdry [1]. Modern fluid catalytic cracking (FCC) was conceived at Exxon and commercially developed in about 1940 [2] using amorphous catalysts. Fluid catalysts are small spherical particles ranging from 40 to 150 um in diameter with acid sites capable of cracking large petroleum molecules to products boiling in the gasoline range. One advantage of the FCC process is the absence of the diffusion limitations present in conventional gas oil cracking due to the small size of the catalyst particle. Since 1964 virtually all catalysts contain faujasite, a stable, large pore, Y-type zeolite dispersed in a silica/alumina matrix [3]. The catalytic aspects of contemporary FCC processes have been reviewed by Venuto and Habib [4], Gates, Katzer, and Schuit [5], Magee and Blazek [6], and Magee [7]. A more recent update of refinery trends has been made available by Blazek [8].     

Preparation and Properties of Fluid Cracking Catalysts for Residual Oil Conversion

Catalytic cracking of petroleum to produce gasoline began in about 1912. The early pioneering work was carried out by Eugene Houdry [1]. Modern fluid catalytic cracking (FCC) was conceived at Exxon and commercially developed in about 1940 [2] using amorphous catalysts. Fluid catalysts are small spherical particles ranging from 40 to 150 um in diameter with acid sites capable of cracking large petroleum molecules to products boiling in the gasoline range. One advantage of the FCC process is the absence of the diffusion limitations present in conventional gas oil cracking due to the small size of the catalyst particle. Since 1964 virtually all catalysts contain faujasite, a stable, large pore, Y-type zeolite dispersed in a silica/alumina matrix [3]. The catalytic aspects of contemporary FCC processes have been reviewed by Venuto and Habib [4], Gates, Katzer, and Schuit [5], Magee and Blazek [6], and Magee [7]. A more recent update of refinery trends has been made available by Blazek [8].     

Two-stage cracking catalyst of amorphous silica-alumina on Y zeolite for enhanced product selectivity and suppressed coking

A novel bilayer catalyst composed of amorphous silica-alumina (ASA) layer coated on Y zeolite layer is proposed as a fluid catalytic cracking (FCC) catalyst to cause two-stage reactions of pre-cracking and deep-cracking. The bilayer catalyst (Y/ASA) is compared with the usual mixed one (ASA+Y), in catalytic cracking of a feed composed of 1,3,5-triisopropylbenzene and naphthalene. The two catalyst representations were prepared by applying layers of Y zeolite and ASA or both on inert monolith supports. Catalytic cracking experiments were carried out at 300, 350 and 400 °C. Compared to Y+ASA, Y/ASA yielded about 33% and 46% more benzene and toluene, respectively, and 18% less coke in the catalytic cracking at 350 oC. The coke of Y/ASA was less refractory than that of Y+ASA as burnt at lower temperatures, while emitting less carbon monoxide in regeneration. Y/ASA configuration shows promising features as FCC catalysts for increased bottoms cracking and suppressed coking.     

Zeolite Y synthesized with FCC spent catalyst fines: particle size effect on catalytic reactions

In this study, Y zeolite with different particle sizes was synthesized with fines of Fluid Catalytic Cracking (FCC) spent catalyst. The effect of particle size on physicochemical properties of zeolite was systematically investigated. The results showed that zeolites synthesized via in situ crystallization technique exhibited large surface area, high relative crystallinity and high thermal stability. With a decrease of particle size of zeolite, both total acid density and B acid sites increased while acid L sites decreased. The cracking activity for heavy oil and coke resistance of ultra-fine zeolite catalysts were enhanced. Of note is that the desulfurization capability of superfine zeolite catalyst was found to be much higher than that of industrial catalyst.     

Effects of steaming-made changes in physicochemical properties of Y-zeolite on cracking of bulky 1,3,5-triisopropylbenzene and coke formation

The effects of acidic properties and structural changes of Y zeolite, produced by steaming, on the zeolite cracking activity, coking tendency and distribution of various products during catalytic conversion of bulky 1,3,5-triisopropylbenzene (TIPB) are reported. NaY zeolite with framework Si/Al ratio of 2.4 was synthesized by a hydrothermal method and ammonium exchanged. The zeolite was dealuminated by a temperature-programmed steaming to form USY1 and USY2 zeolites with framework Si/Al ratio of 8.1 and 12.3 respectively. The catalysts were characterized by XRD, XRF, SEM, AAS, NH₃–TPD and N₂ adsorption–desorption techniques. The samples were in-situ activated at 748 K and evaluated by TIPB cracking at 623 K. The coke content of the catalyst beds was estimated by TPO using an FT-IR gas cell. The results of activity measurements reveal that the dealuminated zeolites lead to lower cracking activity initially; while, they exhibit higher activity at longer times. In addition, a slight modification of the window diameter of Y zeolite, as revealed by pore size distribution analyses, alters the diffusion limitation of the reactant and products through the pores of the zeolite and significantly affects the adsorbent–adsorbate interactions. TPO experiments show that compared to the precursor zeolite, lower amount of coke is formed on the dealuminated catalysts possessing lower density of acid sites. However, the coke formed on USY samples is heavier than that formed on its precursor Y zeolite. This may be attributed to the larger pores shaped in the dealuminated catalysts which in turn provide suitable places for coke formation and growth.     

Exhausted fluid catalytic cracking catalysts as raw materials for zeolite synthesis

The utilization of exhausted fluid catalytic cracking (FCC) catalysts as raw materials for the zeolite synthesis was analyzed. Samples of the catalysts directly released from FCC units and the corresponding impact grinding pretreated samples were used. Mechanical treatment was observed to decrease catalyst crystallinity and particle size. The catalyst reactivity was analyzed in terms of conversion in zeolite and product properties. Hydrothermal synthesis experiments in NaOH medium were performed. Catalysts conversion in A and X type zeolites was obtained for treated and not treated samples. In particular, high conversion in NaX type were achieved using the more siliceous catalyst, whereas grinding activation produces a decrease of particle size and Al/Si ratio of the zeolites obtained.     

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。     

改性催化裂化催化剂研究进展

对催化裂化催化剂的活性组分Y型分子筛的脱铝改性及抗重金属污染改性方法和改性后的含Y型沸石的性能进行了详细介绍。重点介绍了经特殊改性的催化裂化催化剂在脱硫、多产柴油及多产丙烯等方面的用途,指出应在现有技术基础上重点开发性能更为优良的多用途催化裂化催化剂。     

Spherical mesocellular silica foams: a superior support for hydrodesulfurization of fluid catalytic cracking diesel

High surface area aluminum containing spherical mesocellular silica foams (SMCFs) with ultra-large pore volume and 3D pore size were successfully synthesized through a simple hydrothermal route, and the as-synthesized aluminum containing SMCFs (Al-SMCFs) was applied as the support of NiMo-base catalyst for the hydrodesulfurization (HDS) of fluid catalytic cracking (FCC) diesel. The as-synthesized supports and corresponding catalysts were characterized by powder small X-ray diffraction, nitrogen physisorption, scanning electron microscopy, transmission electron microscopy (TEM), inductively coupled plasma optical emission spectroscopy, and temperature-programmed reduction with H₂. The characterization results showed that, compared with other prepared catalysts (NiMo/Al-SBA-15 and NiMo/Al-KIT-6), the NiMo/Al-SMCFs catalyst possessed the most optimal physicochemical parameters, i.e., ultra-large 3D pore size (42.0 nm), high surface area (330.1 m²·g^?1), and ultra-large pore volume (1.96 cm³·g^?1), resulting in the formation of more homogeneous distribution of octahedral Mo active species and good mass transfer performance. Consequently, the NiMo/Al-SMCFs catalyst displayed the outstanding HDS performance (98.8%) of FCC diesel, confirming that the Al-SMCFs may be a type of promising candidate for oil hydrotreating.     

Fluid catalytic cracking: chemistry

Fluid catalytic cracking (FCC) is the major catalytic refinery process and the chemistry of some of the complex reactions occurring during FCC processing is reviewed and discussed. Experimental results for catalysts based on zeolite Y, and its modifications, and for comparison of zeolite Y and shape-selective catalysts are used to explain features of the underlying chemistry involved in the FCC process.     

Effects of metal modifications of Y zeolites on sulfur reduction performance in fluid catalytic cracking process

The acidity of catalytically active component, e.g., ultra stable Y zeolite (USY), plays an important role in determining their cracking activity and selectivity. To develop advanced sulfur reduction catalytic cracking catalysts, different type of elements were used to modify USY and the resulting catalysts were evaluated in a confined fluidized bed reactor and a micro-activity testing unit. The relation between the acidity of the zeolite and the conversion of sulfur compounds as well as the distributions of fluid catalytic cracking (FCC) products were discussed. The results showed that the rare earth (RE) metal can stabilize the catalyst and increase the conversion, but cannot increase the selectivity to thiophene compounds; V can reduce the sulfur content by 36.3 m%, but decreases the overall conversion compared with the base catalyst. An optimum catalyst was obtained by the combined RE and V modification, over which the sulfur content in FCC gasoline can be decreased and the selectivity for the target products can be improved, with the sulfur content reduced by 30 m% and the selectivity to coke even decreased by 0.20 m% at a comparable conversion level of the base catalyst.     

Increased Metal Utilization in Carbon‐Supported Pt Catalysts by Adsorption of Preformed Pt Nanoparticles on Colloidal Silica

Pt/C electrocatalysts, aimed at maximizing the electrochemical surface area (ECSA) and consequently the specific mass activity of fuel cell reactions, are obtained by firstly depositing Pt nanoparticles on colloidal silica (Pt‐silica), followed by the adsorption of the latter onto a carbon support. This method of catalyst preparation increases Pt metal utilization and generates accessible void space in the interpenetrating particle network of carbon and silica for the facile transport of reactants and products. Both electrochemical hydrogen adsorption/desorption and CO oxidation measurements show an increase in the ECSA using this approach. Methanol electrooxidation is used as a test reaction to evaluate the catalytic activity. It is found that the silica modified catalyst is three times as active as a catalyst prepared without silica, under otherwise identical conditions.     

Impact of accessibility and acidity on novel molecular sieves for catalytic cracking of hydrocarbons

The catalytic properties of extra-large pore aluminosilicate MCM-41, silicon containing VPI-5 and aluminium containing ETS-10 were investigated by MAT (Micro Activity Test) using n-hexadecane and 1,3,5-triisopropylbenzene as the model feeds and were then compared with the results obtained from Y zeolite in the H-form and a commercial FCC (Fluid Catalytic Cracking) catalyst. It could be demonstrated that not only the acidic properties of the investigated materials, but also the accessibility to the internal active sites of the investigated materials have a significant influence on activity and selectivity. It can be assumed that, by optimising structural and chemical properties, the mesoporously organised MCM-41 and related materials are suitable as active components in cracking catalysts for “deeper” cracking of high boiling hydrocarbons.     

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.     

中大孔催化裂化催化剂研究进展

发展中大孔型催化剂是催化裂化催化剂的主要发展方向之一,催化裂化催化剂中引入中大孔的主要方法有高岭土酸碱改性法、引入大孔硅铝基材料法、引入介孔分子筛法、原位晶化法和模板法。酸碱改性高岭土的孔结构受原料影响较大,孔径一般小于10 nm;制备大孔硅铝基材料替代拟薄水铝石可有效改善催化剂的孔结构,但应关注对催化剂强度的影响;分子筛中引入介孔又包括水热处理法,酸、碱处理法和引入不稳定位点法,工业应用范围广,但处理过程中易造成Y型分子筛结晶度下降,并缺乏连续、贯通型孔道;原位晶化法是工业上较成功的中大孔催化剂制备方法,但能耗相对高,流程长;模板法可通过改变模板类型、含量对催化剂孔结构调变,但应关注环保及催化剂强度问题。     

Kinetic and catalytic performance of a BI‐porous composite material in catalytic cracking and isomerisation reactions

Catalytic behaviour of pure zeolite ZSM‐5 and a bi‐porous composite material (BCM) were investigated in transformation of m‐xylene, while zeolite HY and the bi‐porous composite were used in the cracking of 1,3,5‐triisopropylbenzene (TIPB). The micro/mesoporous material was used to understand the effect of the presence of mesopores on these reactions. Various characterisation techniques, that is, XRD, SEM, TGA, FT‐IR and nitrogen sorption measurements were applied for complete characterisation of the catalysts. Catalytic tests using CREC riser simulator showed that the micro/mesoporous composite catalyst exhibited higher catalytic activity as compared with the conventional microporous ZSM‐5 and HY zeolite for transformation of m‐xylene and for the catalytic cracking of TIPB, respectively. The outstanding catalytic reactivity of m‐xylene and TIPB molecules were mainly attributed to the easier access of active sites provided by the mesopores. Apparent activation energies for the disappearance of m‐xylene and TIPB over all catalysts were found to decrease in the order: E_BCM > E_ZSM‐5 and E_BCM > E_HY, respectively. © 2012 Canadian Society for Chemical Engineering     

Synthesis of mesoporous MFI zeolite by dry gel conversion with ZnO particles and the catalytic activity on TMB cracking

A facile synthesis method for mesoporous MFI zeolite (MMZ) has been developed. MFI zeolite was synthesized by a dry gel conversion in the presence of ZnO nanoparticles with a size of 20 nm. The as-synthesized MFI zeolite included crystalline layered zinc silicate and already possessed 5–15 nm mesopores. After calcination, MMZ/zinc silicate composite was treated with hydrochloric acid to remove unreacted ZnO particles. The micropore (1–2 nm) volume was increased after the HCl treatment, suggesting that ZnO nanoparticles (1–2 nm) remained during crystallization as well as zinc silicate. The catalytic activity of MMZ on 1,3,5-trimethylbenzene (TMB) cracking was compared with that of conventional MFI nanocrystals with a size of 80–100 nm. The conversion of TMB on MMZ was much higher than that on the MFI nanocrystals even though crystal size of MMZ is larger than the conventional MFI zeolite. These results suggest that acid sites on the internal surface of mesopores of MMZ contribute to the high conversion of TMB.