FCC废催化剂中金属分布规律及赋存状态研究进展

FCC催化剂是当前用量最大的炼油催化剂,FCC废催化剂的综合处理和资源化利用必然会取代现有的填埋处理方式。综述近年来国内外关于FCC废催化剂中污染金属的分布规律及存在形态方面的研究进展。对于FCC废催化剂的处理和利用,明确污染金属分布状态和物质存在形式将有利于处理方案的选择与制定。在各种污染金属元素中,Ni是FCC废催化剂中最为关键的一种污染金属,对于Ni是以何种化合物形式存在,仍有待进一步的研究。     

FCC废催化剂金属形态特征及其生态风险评价

旨在评价不同炼化装置FCC废催化剂的金属含量、赋存形态特征及生态风险。本文采集了5种不同炼化厂的FCC废催化剂,分别测定了每种废催化剂Fe、Al、Ni、V、Sb和Co等6种金属的总含量和4种赋存形态含量,采用风险评价编码指数（RAC）、原生相与次生相比值（RSP）及结合强度系数（I_R）评价了5种FCC废催化剂各类金属的潜在生态风险。结果表明,不同废催化剂样品间的金属总含量差别较大,受试样品中金属总含量均未达到《危险废物鉴别标准》的限值,且除部分废催化剂的金属V和Sb外,其他金属含量指标均可达到二类建设用地的土壤环境质量标准;5种FCC废催化剂中各类金属的4种赋存形态中,可还原态在金属V中的占比最高,其他金属均以残渣态为主要成分;5种FCC废催化剂中金属V的RSP值较高,I_R值较低,具有较高的潜在生态风险,其他5种金属的潜在生态风险低。     

废FCC催化剂在LPG吸附脱硫中的资源化利用

金属污染是导致流化催化裂化（FCC）催化剂失活的重要因素,充分利用沉积的重金属是废FCC催化剂资源化的关键。本文将废FCC催化剂引入到轻质油品吸附脱硫领域,以脱除液化石油气（LPG）中的二甲基二硫醚作为考核目标,验证了废FCC催化剂作为脱硫剂的可行性。除去废FCC催化剂表面积炭后,其脱硫性能得到明显改善,在常温、质量空速为4.0h^-1的条件下,LPG中硫化物质量分数从382mg/m³脱除至40mg/m³。镧、铁、镍、钒、钙、锑6种金属在新鲜催化剂和焙烧后废催化剂上的总质量分数从10.2%升高至46.6%,6种金属按照对应含量分别固载在新鲜催化剂上,脱硫效果较未改性新鲜催化剂均有明显提升。验证实验表明,导致FCC催化剂失活的金属具有较高脱硫活性,废FCC催化剂作为轻质油品脱硫剂具备工业前景。     

危险废物利用与处置在催化裂化催化剂制备过程中的应用研究

为了减少危险废物处理成本,提高处理效率,研究分析在催化裂化催化剂制备过程中产生的FCC废催化剂,利用高温熔融法对其资源化利用与处置。结果表明,高温熔融法处理技术对废催化剂上的重金属Ni、V具有一定的固化作用,对废催化剂实现资源化利用,以此减少环境污染,对危险废物的处理成本有所降低。经过深入研究和技术创新,为实现危险废物减量化、资源化和无害化的目标提供有力支持。     

FCC废催化剂综合利用研究

对目前国内外FCC废催化剂再生利用及化学方法回收稀土La、Ce进行了比较研究,认为FCC废催化剂磁分离技术和化学分离技术并没有完全解决催化剂二次利用,建议加强FCC废催化剂直接用作水泥填料和制作稀土陶器的填料的研究,直接解决FCC废催化剂对环境的污染。     

废FCC催化剂协同臭氧催化氧化处理石化污水

随着石油化工行业的发展,石化企业每年都要排放大量石化污水,这些污水含有大量难降解有机物及其他有害物质,不仅污染环境,还会危及人类的健康。臭氧催化氧化技术能有效地降解污水中的难降解有机物,但存在催化剂制备成本高、活性组分易流失等缺陷。同时,炼厂固废的产生量也在逐年增加,如何科学有效的对这些固废进行综合利用成为了石化行业的"老大难"课题。因此,以炼厂固废处理石化污水的"以废治废"的技术应运而生,其中,废FCC催化剂(sFCCc)中含有高价态的V(V4+、V5+)、Ni(Ni2+)、Fe(Fe2+、Fe3+)等金属氧化物,以废FCC催化剂协同臭氧催化氧化(sFCCc-O)处理污水有巨大的潜力。     

催化裂化金属钝化剂研究进展

重油中钒(V)、镍(Ni)在FCC过程中会沉积在催化剂上,导致催化剂失活。金属钝化剂是降低钒、镍对FCC催化剂污染的有效方法。主要分为单一和复合多功能两大类。文中介绍了重金属钒、镍对催化剂污染机理,综述了各种钝化剂研究进展及工业应用状况,为我们开发新型金属钝化剂奠定一定基础,指出无毒、高效、水溶性复合多功能金属钝化剂是今后的主要发展方向。     

重油催化裂化的金属钝化剂

重油中所含的金属Ni、V、Na在流化催化裂化 (FCC)过程中 ,会污染催化剂 ,导致催化剂失活。本文综述了国内外金属钝化剂的研究进展 ,提出研制无毒、高效以及多功能的金属钝化剂是今后发展的方向。     

催化裂化废催化剂再利用的途径

介绍了流化催化裂化(FCC)废催化剂用于回收金属、作为原料合成分子筛和水泥、吸附有害物质、降解废塑料等几种再利用的途径。将FCC废催化剂作为二次资源,加以回收利用,不仅可以减轻环境污染,还可以充分利用资源,生产高附加值产品,带来经济效益,从根本上解决FCC废催化剂的处置问题。     

废FCC催化剂及烟气脱硫废渣的处理研究进展及应用

2016年新颁布《国家危险废物名录》将废FCC催化剂定性为危险废物,另外烟气脱硫废渣主要成分为废FCC催化剂,所以对废FCC催化剂及烟气脱硫废渣资源化利用的问题亟待解决。本文介绍了废FCC催化剂及烟气脱硫废渣的失活原因与危害,论述了现阶段国内外废FCC催化剂的主要处理技术和利用情况,主要包括物理分离法、化学再生技术、废水吸附剂、精制润滑油和石蜡、水泥辅料等,为未来废FCC催化剂的减量化、无害化、再生与资源化提供工业应用参考。     

A comparative study of liquid product on non-catalytic and catalytic degradation of waste plastics using spent FCC catalyst

Non-catalytic and catalytic degradation of waste plastics (high-density polyethylene (HDPE), low-density polyethylene (LDPE), polypropylene (PP) and polystyrene (PS)) using spent fluid catalytic cracking (FCC) catalyst into liquid product were comparatively studied with a stirred semi-batch reactor at 400 ‡C, under nitrogen stream. Liquid product characteristics were described by cumulative distribution as a function of lapse time of reaction, paraffin, olefin, naphthene and aromatic (PONA) composition, and also carbon number distribution on plastic type of reactant. For degradation of waste PE with relatively high degradation temperature, the effect of adding spent FCC catalyst greatly appeared on cumulative distribution of liquid product with a reaction lapse time, whereas those for waste PP and PS with low degradation temperature showed a similar trend in both non-catalytic and catalytic degradation at 400 ‡C. In PONA and carbon number distribution of liquid product, the characteristics of waste PS that was mainly degraded by end chain scission mechanism were not much altered in presence of spent FCC catalyst. However, waste polyolefinic polymer that was degraded by a random chain scission mechanism significantly differed on PONA and carbon number distribution of liquid product with or without spent FCC catalyst. The addition of spent FCC catalyst in degradation of polyolefinic polymer, which economically has a benefit in utilization of waste catalyst, significantly improved the light olefin product by its high cracking ability and also the aromatic product by cyclization of olefin as shape selectivity in micropore of catalyst.     

Review on the deactivation of FCC catalysts by cyclic propylene steaming

The deactivation of FCC catalysts in small-scale units in the presence of contaminant metals has been the industry workhorse for a number of years due to the robustness and simplicity of such methods.

A major advance in the deactivation of metallated catalysts on a small-scale that better simulated the performance of commercial FCC catalyst, was the introduction of the cyclic propylene steaming (CPS) method. In the CPS protocol, FCC catalyst is impregnated with vanadium and nickel prior to deactivation in reduction–oxidation cycles and the latter provides significant advantages over traditional methods such as the Mitchell approach. In certain situations, however, the contribution of vanadium to catalyst deactivation is over-emphasized in the CPS method, and therefore this method has been developed further.

This paper describes a number of modifications that have been made to the CPS method to further attenuate the destructive effects of vanadium on the FCC catalyst during deactivation. This includes exposing the metallated catalyst to pre-stabilisation steps with reduction-oxidation cycles and changing the ratio of the time the catalyst spends in reducing and oxidising environments during the CPS cycles. The comparison of activity and selectivity data obtained from FCC catalysts having age distribution with those obtained from CPS showed that both scenarios gave the same catalyst ranking.

These investigations have also shown that the use of reduction–oxidation cycles better simulates the deactivation of FCC catalysts in the absence of contaminant metals. These investigations have also shown that the use of reduction–oxidation cycles better simulates the deactivation of FCC catalysts in the absence of contaminant metals “the part” than traditional deactivations in a 100% steam atmosphere.     

Fluid catalytic cracking technology: current status and recent discoveries on catalyst contamination

The fluid catalytic cracking (FCC) technology is one of the pillars of the modern petroleum industry which converts the crude oil fractions into many commodity fuels and platform chemicals, such as gasoline. Although the FCC field is quite mature, the research scope is still enormous due to changing FCC feedstock, gradual shifts in market demands and evolved unit operations. In this review, we have described the current status of FCC technology, such as variation in the present day feedstocks and catalysts, and particularly, great attention is paid to the effects of various contaminants of the FCC catalysts of which the latter part has not been sufficiently documented and analyzed in the literature yet. Deposition of various contaminants on cracking catalyst during FCC process, including metals, sulfur, nitrogen and coke originated from feedstocks or generated during FCC reaction constitutes a source of concern to the petroleum refiners from both economic and technological perspectives. It causes not only undesirable effects on the catalysts themselves, but also reduction in catalytic activity and changes in product distribution of the FCC reactions, translating into economic losses. The metal contaminants (vanadium (V), nickel (Ni), iron (Fe) and sodium (Na)) have the most adverse effects that can seriously influence the catalyst structure and performance. Although nitrogen and sulfur are considered less harmful compared to the metal contaminants, it is shown that pore blockage by the coking effect of sulfur and acid sites neutralization by nitrogen are serious problems too. Most recent studies on the deactivation of FCC catalysts at single particle level have provided an in-depth understanding of the deactivation mechanisms. This work will provide the readers with a comprehensive understanding of the current status, related problems and most recent progress made in the FCC technology, and also will deepen insights into the catalyst deactivation mechanisms caused by contaminants and the possible technical approaches to controlling catalyst deactivation problems.     

Thermal and catalytic degradation of waste high-density polyethylene (HDPE) using spent FCC catalyst

Thermal and catalytic degradation using spent fluid catalytic cracking (FCC) catalyst of waste high-density polyethylene (HDPE) at 430 °C into fuel oil were carried out with a stirred semi-batch operation. The product yield and the recovery amount, molecular weight distribution and paraffin, olefin, naphthene and aromatic (PONA) distribution of liquid product by catalytic degradation using spent FCC catalyst were compared with those by thermal degradation. The catalytic degradation had lower degradation temperature, faster liquid product rate and more olefin products as well as shorter molecular weight distributions of gasoline range in the liquid product than thermal degradation. These results confirmed that the catalytic degradation using spent FCC catalyst could be a better alternative method to solve a major environmental problem of waste plastics. This paper is dedicated to Dr. Youn Yong Lee on the occasion of his retirement from Korea Institute of Science and Technology.     

From waste to best: excellent desulfurization performance of spent FCC catalyst

Fluidized catalytic cracking (FCC) is an important link in heavy oil processing. Industrial FCC catalyst which mainly consists of molecular sieves, substrates and adhesives is used in large quantities every year. Spent FCC catalyst is one kind of hazardous solid waste that is hard to handle. In this paper, we used a spent FCC catalyst as a desulfurization adsorbent, and show that it displays advanced desulfurization property. Furthermore, regeneration experiment showed that calcination was an effective method to remove the sulfides adsorbed in spent FCC catalyst, after four cycles it still owned a high sulfur adsorption ability. The results of metal impregnation indicated that the high ability to remove sulfur in LPG was due to those metals deposited on WC. The sulfur removal further increased by calcination of the spent catalyst since carbon deposition on the catalyst surface which blocked the active sites was minimized by calcination, thus leading an increase in the number of active sites available.     

Effect of metals poisoning on FCC products yields: studies in an FCC short contact time pilot plant unit

In this work the effects of two metal poisons (Ni, V) on FCC products were investigated in an FCC pilot plant. The most important effects of metals were found on the gasoline, coke and H₂ yields. A comparison study of the metal distribution in the catalyst particles aged in the FCC pilot plant, a CDU and an industrial FCCU was also performed using a SEM–EDS method. SEM results showed that the metal profiles from CDU samples simulate more satisfactorily the profiles of the E-cat than that from the FCC pilot plant.     

Equilibrium catalyst from a fluidized catalytic cracking unit separated by metal content by using carbon nanotubes and a biphasic system

During fluid catalytic cracking (FCC) operations FCC catalyst particles become contaminated with various metals. These metals impact FCC performance and currently requires equilibrium catalyst (ECAT) mixtures consisting of a blend of FCC particles with a time spent in the reactor ranging from minutes to several months to be continuously extracted and sold as low value products or sent to landfills. Here a unique method to recycle FCC ECAT particles is presented, which separates ECAT particles by metal content by synthesizing carbon nanotubes and nanofibers on the ECAT particles surface and using a biphasic system. ECAT with low metal content can be sent back to the FCC unit for further use while ECAT with high metal content can be used for other purposes. Further, we show these treated ECAT materials of high metals content will absorb oil on the surface of water and may prove useful for oil spill clean-up applications.     

Challenges, catalyst technology and catalytic solutions in resid FCC

The concurrent evolution of resid fluid catalytic cracking (RFCC) processes and catalyst technology over the years is discussed. Resid FCC catalysts today are designed making use of the following features: (a) High activity, selectivity and metals resistant zeolites; (b) Highly accessible catalyst architecture for optimal site utilization, bottoms cracking, Conradson carbon residue (CCR) conversion and easy stripping; and (c) Specially designed metal-support interaction systems to reduce the detrimental effects of metal contaminants. The future will require even more robust RFCC catalyst systems. These catalyst systems should be very accessible and effective in cracking large hydrocarbon molecules and should have the capability to handle contaminants such as metal-, sulfur-, and nitrogen-compounds. Conversion of CCR to non-coke components will be crucial in order to reduce the delta coke and hence improve the processability of heavier resids. Processability here is meant not only in terms of coke and heat balance considerations, but also involves avoiding fouling of the unit hardware by unconverted heavy hydrocarbons and coke precursors. Last, but not the least, present and future catalyst technology must be formulated and adapted to the specific commercial process unit needs and constraints, thus leading to the most cost effective solution for the refiner.     

Catalytic degradation of waste polyolefinic polymers using spent FCC catalyst with various experimental variables

Liquid-phase catalytic degradation of waste polyolefinic polymers (HDPE, LDPE, PP) over spent fluid catalytic cracking (FCC) catalyst was carried out at atmospheric pressure with a stirred semi-batch operation. The effect of experimental variables, such as catalyst amount, reaction temperature, plastic types and weight ratio of mixed plastic on the yield and accumulative amount distribution of liquid product for catalytic degradation was investigated. The initial rate of catalytic degradation of waste HDPE was linearly increased with catalyst amount (4-12 wt%), while that was exponentially increased with reaction temperature (350-430 ‡C). Spent FCC catalyst in the liquid-phase catalytic degradation of polymer was not deactivated fast. The product distribution from catalytic degradation using spent FCC catalyst strongly depended on the plastic type. The catalytic degradation of mixed plastic (HDPE: LDPE: PP: PS=3: 2: 3: 1) showed lower degradation temperature by about 20 ‡C than that of pure HDPE.