FCC钝化剂研究进展

流化催化裂化过程中,沉积在催化剂上的金属Ｎｉ,Ｖ会导致催化剂严重失活,加入金属钝化剂是解决上述问题的经济有效的方法。本文综述了金属钝化剂的研究进展,指出研制无毒,高效的钝镍剂,钝钒剂以及钝镍钝钒双功能钝化剂是今后的发展的主导方向。     

硼基催化裂化钝镍剂的工业应用及其钝镍机理

使用B基无毒催化裂化钝镍剂可使汽油收率增加 1% ,氢气和焦炭产率分别下降 35 %和 10 %以上 ,该剂的整体钝镍性能不低于目前应用广泛的锑基有毒钝镍剂YXM。结合MAT ,TPR ,XRD等实验方法和量子化学计算理论研究阐明了该钝镍剂的钝镍机理 :在FCC再生条件 (约 70 0℃ ,氧化性气氛 )下 ,由于硼基钝镍剂热分解生成B2 O3 并与NiO反应生成Ni2 B2 O5,增加了Ni2 + 的LUMO能量 ,降低了Ni2 + 在FCC反应条件 (约 5 0 0℃ ,还原性气氛 )下的还原度 ,抑制了Ni0 的强催化脱氢活性 ,从而达到钝镍的目的     

国内重油催化裂化催化剂工业应用现状

介绍了国内典型重油催化裂化催化剂工业应用现状。分别阐述高掺渣比催化剂、抗重金属型催化剂、增产低碳烯烃催化剂和加工M-100专用CORH、CMO催化剂的使用情况,并对各催化剂的性能进行了综合比较,指出不同催化剂所适用原料的特性,最后提出了新型重油催化裂化催化剂的发展趋势。     

磷酸盐对催化剂沉积镍钝化机理及其工业应用

磷酸盐无毒钝镍剂可有效钝化催化裂化催化剂上沉积镍对催化剂的污染,该剂的整体钝镍性能不低于目前应用广泛的锑基有毒钝镍剂YXM。结合MAT、TPR、XRD等实验方法和量子化学计算理论研究阐明了该钝镍剂的钝镍机理：在FCC再生条件（约700℃,氧化性气氛）下,由于磷基钝镍剂热分解生成P2O5并与NiO反应生成NiP4O11,增加了Ni^2 的LUMO能量,降低了Ni^2 在FCC反应条件（约500℃,还原性气氛）下的还原度,抑制了Ni^0的强催化脱氢活性,从而降低催化裂化过程的H2和焦炭产率,提高汽油收率,达到钝镍的目的。     

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.     

掺海泡石原位晶化催化裂化催化剂的研究

用海泡石和高岭土混合物为原料,以原位晶化技术制备催化裂化(FCC)催化剂,考察了海泡石对结晶度、硅铝比和抗钒性能的影响。结果表明掺海泡石的原位晶化产物与未加海泡石相比,结晶度较低,硅铝比较高,海泡石含量在5%~30%范围时,结晶度和硅铝比变化不大。该催化剂水热活性(100%水蒸汽、800℃、17h)较未加海泡石低,但钒污染(质量分数5×10-3)后活性保留率却高出25%,抗钒能力较高。     

Quantitative determination of ZrC in new ceramic materials by Fourier transform infrared spectroscopy

Zirconium carbide-based biomorphic ceramics have been manufactured by vacuum infiltration of zirconium-oxychloride (ZrOCl₂·8H₂O) sol into natural wood. After vacuum-assisted infiltration, the specimens were dried in air and pyrolysed at 800 °C in Ar-atmosphere. The infiltration and drying process were repeated up to four times. Finally, the specimens were hold at 1550 °C in a vacuum furnace to form ZrC. The results of the process of synthesis have been studied using scanning electron microscopy (SEM). For evaluating the yield of the synthesis, a new method by Fourier transform infrared spectrometry (FTIR) has been developed for the direct determination of ZrC by absorbance measurements in KBr pellets. The procedure was based on the use of the ratio between the absorbance of the characteristic band of zirconium carbide and those of an oxalate internal standard added to samples. A multivariate calibration strategy based on inverse least squares and the standard addition approach was employed for quantification. The results obtained for all ZrC-ceramics studied were satisfactorily compared with those obtained by X-ray diffractometry (XRD). The proposed method was also applied to the analysis of synthetic samples prepared by mixing pyrolyzed wood with ZrC, the results indicated good recovery in all instances.     

钒对FCC催化剂脱除噻吩类硫化物性能的影响

催化裂化过程(FCC)中使用催化剂脱硫对生产清洁燃料具有重要意义。文中通过文献调研,阐述了噻吩类硫化物在FCC催化剂上的裂化依赖于B酸和L酸的协同作用原理,指出以L酸碱对化合物修饰FCC催化剂可改善其表面的弱L酸分布,增强催化剂对噻吩类硫化物的选择性吸附能力,提高FCC催化剂脱除噻吩类硫化物性能。氧化钒作为典型的L酸碱对化合物,利用其修饰FCC催化剂可改善裂化催化剂的脱硫活性。鉴于氧化钒对FCC催化剂的活性组分分子筛存在一定的破坏作用,FCC催化剂的载体是较适宜的修饰位置。低价态钒较高价态钒对噻吩有着更强的化学吸附能力,因而采用还原预处理后的催化剂可得到较好的脱硫效果。     

Study of the accessibility effect on the irreversible deactivation of FCC catalysts from contaminant feed metals

Two commercial FCC catalysts were investigated to explore the effect of their different accessibility on the catalyst activity, selectivity and deactivation due to deleterious feed metals (V and Ni). Feed metal Fe was not included in the present study. E-Cats (equilibrium samples from a commercial FCC unit) of both FCC catalysts and the corresponding laboratory-deactivated samples (applying the cyclic deactivation (CD) and the cyclic propylene steaming (CPS) methods) were thoroughly studied. Extensive characterization (XRD, N₂ physisorption, measurement of Akzo Accessibility Index (AAI), SEM-EDS analysis) of all samples was realized to investigate variations in their crucial properties due to metal deposition. Comparison of E-Cats, CD and CPS samples revealed a very different nickel deposition profile over the CPS samples. In all cases, V was homogenously distributed throughout the particle, as expected due to its mobility. Ni–Al mixed phases, observed on the E-Cat samples, were probably formed during ageing and are expected to be inactive. The absence of such phases on the laboratory-deactivated samples can be attributed both to the inability of the two deactivation methods to simulate metal ageing during commercial utilization of the FCC catalyst and the absence of Fe incorporation during laboratory deactivation. All catalytic samples (E-Cats and artificially deactivated FCC catalysts) were evaluated in the laboratory using two bench-scale Microactivity Test (MAT) units of different reactor configuration: fixed-bed (SCT-MAT unit) and fluid-bed (AUTOMAT unit). Similar ranking of the catalysts is achieved when using both units. However, AUTOMAT unit seems to provide a clearer diversification of catalysts with different accessibility. Both laboratory deactivation methods seem to be rather inefficient in simulating the real deactivation, since they are always exaggerating metal effects.     

湛江高岭土作FCC催化剂载体可行性试验研究

对湛江高岭土的物化性质进行分析测试,并对以湛江高岭土为载体制备的半合成催化剂进行评价。结果表明,湛江高岭土晶体结构以片状为主,粒度分布较为集中,化学组成与苏州高岭土基本相当;采用湛江高岭土为载体的催化剂,其质量指标和裂化性能与对比样相当,可以满足FCC催化剂质量指标的要求。     

新型沸石分子筛的研究进展及其在FCC催化剂中的应用

介绍了用于FCC催化剂中的几种新型沸石分子筛的结构特征,并综述了其研究进展,以及在FCC催化剂中应用时,存在的问题和前景展望。根据目前炼油技术的需求多样化,指出特种分子筛催化材料的技术发展趋势。     

Structural characterization of FCC feeds from Indian refineries by NMR spectroscopy

Fluid catalytic cracking (FCC) feeds from four Indian refineries are structurally characterized by ¹H, gated-decoupled ¹³C, distortionless enhancement by polarization transfer (DEPT) and 2D ¹H–¹³C HETeronuclear CORrelation (HETCOR) and other 2D nuclear magnetic resonance (NMR) methods. Detailed structural analyses are completely supported by a range of NMR information including chemical shifts of ¹H and ¹³C, CH_n type distributions and ¹H –¹³C connectivities. The average structural parameters like branching sites, average number of branching per molecule, average length of side chains, percentage of saturates, aromatics and naphthenes are obtained from these NMR data. A novel approach based on “multipoint spline base line correction” is employed for estimation of naphthenes and n-paraffins that gives better quantitative estimation than the conventional methods. In this paper, importance is given to the study of those structural parameters that plays a key role in cracking chemistry as well as coke forming tendency of the feedstock. To the best of our knowledge, this is the first attempt to characterize and quantitatively estimate compositions of the high boiling fractions of petroleum feed by NMR methods and especially the complex structure of vacuum gas oil (VGO) fractions used in Indian refineries. The importance of this paper is to help in optimizing the product slate of Indian refineries through proper feedstock blending using few hundreds of million metric tons (MMT) of crude oil consisting of blends of light crudes with different heavy crudes and bottom of the barrel due to escalating cost of crudes.     

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.     

Vanadia layers supported on TiO2/SiO2 mixed oxides — An ESR and Raman investigation

ESR and Raman spectroscopy have been used to characterize monolayers of vanadia, which had been immobilized on titania and on a 20% TiO₂/80% SiO₂ mixed oxide support from a vanadyl alkoxide precursor. Characteristic vibrations observed in the Raman spectrum, as well as UV-visible reflection data, indicate that the most abundant vanadia species on the surface consists of disordered polymeric arrays: the central vanadium ion is surrounded by the tightly bound vanadyl oxygen, four oxygen ions in the basal plane, and a distant sixth oxygen ligand in bridging position to the support. From the ESR spectra the principal values ofg andA tensors are obtained, and their dependence on the support material and on the vanadia loading is investigated. Comparison with TPR measurements indicates that for structurally and chemically similar catalysts, the ESR-derived deviationg = g – g _e from the free electrong value provides a useful measure of the V=O bond strength.     

Interaction between ammonium sulfate-iron oxide shown by ESR and Mössbauer spectroscopy

The ammonium sulfate-iron oxide system treated at different temperatures has been characterized by ESR, IR and Mössbauer spectroscopy. Results show that during the heat treatment some interaction between ammonium sulfate and iron oxide takes place. As a result of this interaction a surface sulfato complex of iron is formed. The complex is involved in the sites responsible for activity for acid catalytic esterification. Above 573 K, the sulfato complex will gradually decompose with a further increase in temperature. A new structure scheme of the sulfato complex is proposed.     

Recycling polystyrene into fuels by means of FCC: performance of various acidic catalysts

In accordance with the option of recycling plastics into fuels by dissolving them in standard feedstocks for the process of catalytic cracking of hydrocarbons, FCC, various acidic catalysts (zeolites ZSM-5, mordenite, Y, and a sulfur-promoted zirconia) were tested in the conversion of polystyrene dissolved into inert benzene at 550°C in a fluidized-bed batch reactor. Experiments were performed with very short contact times of up to 12 s. Main products were in the gasoline range, including benzene, toluene, ethylbenzene, styrene, and minor amounts of C_9–12 aromatics and light C₅₋ compounds. Coke was always produced in very significant amounts. All the products can be justified with basis on the properties of each catalyst and the various possible catalytic reaction pathways: cracking after protolytic attack on the polymer fragments, styrene oligomerization and subsequent cracking, or hydrogen transfer to styrene. Styrene would be mainly produced in this system from thermal cracking of the polymer as the initial step. If present, shape selectivity effects due to catalyst structure can influence significantly the prevalence of the various reactions, because they would interfere with those undergoing bulky transition states, like styrene oligomerization or hydrogen transfer. Even though sulfur-promoted zirconia is highly acidic, the low proportion of Brønsted-type acid sites does not allow the occurrence of secondary styrene reactions. It was shown that most favorable product distributions (higher yields of desirable products) are obtained on equilibrium commercial FCC catalysts.     

钒对裂化催化剂的影响及流化催化裂化抗钒助剂的开发

研究了钒对分子筛和催化剂性能的影响 ,并开发出一种高活性固体的流化催化裂化抗钒助剂。随着钒含量的增加 ,分子筛的结晶度、比表面积、孔体积呈单调下降 ;而催化剂的催化活性大幅降低 ,选择性变差。抗钒助剂与其他类型的催化剂复配后 ,显示出较强的抗钒性能 ,能明显改善裂化产物的汽油、焦炭的选择性。     

硫酸铝合成拟薄水铝石的研究及在催化裂化催化剂上的应用

报道了以硫酸铝为原料合成拟薄水铝石的工艺以及该工艺所制拟薄水铝石用于FCC催化剂的制备,结果表明：以硫酸铝合成的拟薄水铝石具有杂质少,工艺简单,稳定的特点：以该工艺合成的拟薄水铝石制备的催化剂,比工业拟薄水铝石所制催化剂,并微反催化剂活性提高了3％,     

半再生催化重整装置掺炼催化裂化汽油的工业应用

总结了中国石油华北石化公司应用DN-200催化剂R-86催化剂在重整装置进料中掺炼催化汽油的工业运转情况,其成功应用为解决重整装置原料不足问题开辟了一条有效途径,对国内部分炼油厂具有借鉴意义。     

Effect of metal—organic compounds on thiophene hydrodesulphurization over sulphided Co(Ni)Mo/Al2O3 catalysts

Deactivation effects in hydrodesulphurization of thiophene in a pulse reactor over cobalt and nickel promoted Mo/Al₂O₃ catalysts and with vanadium and nickel naphthenate additions were studied. The catalysts were sulphided with CS₂ in hydrogen, and an initial reduction in hydrogen was found to be unnecessary. In the hydrodesulphurization of thiophene smaller changes are observed. A fast initial coking effect is indicated. After regeneration, strongly bonded sulphate species are obtained. Deactivation by the addition of nickel or vanadium naphthenate in a low concentration works similarly. At higher doses, vanadium naphthenate affects both catalysts more strongly than nickel naphthenate. X-ray photoelectron spectroscopy indicates that the metal compounds deposit to a higher extent at the catalyst particles' exterior than at interior surfaces at high levels of additions.