催化裂化催化剂再生过程中的氮化学进展

从流化催化裂化待生催化剂中含氮化合物的主要类型和生成机制、再生过程中含氮化合物的转化途径以及降低再生过程中氮氧化物排放的相应控制措施等几个方面,综述了流化催化裂化催化剂再生过程中的氮化学研究进展。     

A molecular kinetic model incorporating catalyst acidity for hydrocarbon catalytic cracking

This work built a molecular-level kinetic model for hydrocarbon catalytic cracking, incorporating the catalyst acidity as the parameter to estimate reaction rates. The n-decane and 1-hexene co-conversion catalytic cracking process was chosen as the studying case. The molecular reaction network was automatically generated using a computer-aided algorithm. A modified linear free energy relationship was proposed to estimate the activation energy in a complex reaction system. The kinetic parameters were initially regressed from the experimental data under several reaction conditions. On this basis, the product composition was evaluated for three catalytic cracking catalysts with different Si/Al. The Bronsted acid and Lewis acid as the key catalyst properties were correlated with kinetic parameters. The built model can calculate the product distribution, gasoline composition, and molecular distribution at different reaction conditions for different catalysts. This sensitive study shows that it will facilitate the model-based optimization of catalysts and reaction conditions according to product demands.     

Regeneration of cracking catalyst influence of the homogeneous CO postcombustion reaction

Accompanying the fast burning of coke on a cracking catalyst is the oxidation of the coke burning product, carbon monoxide. This carbon monoxide combustion involves a homogeneous and a catalytic reaction. The homogeneous reaction was isolated by injecting pulses of CO, CO₂ and O₂ into a laboratory scale reactor at controlled temperature and pressure. The coke burning and catalytic CO combustion reactions were studied by oxidizing coke deposited on a zeolitic catalyst in the same microcatalytic reactor. The role of homogeneous CO oxidation during coke combustion under these conditions was determined.     

烯烃裂解增产丙烯催化剂再生性能

由于烯烃裂解技术反应自身的特点,催化剂容易积炭失活,需要进行多次再生,因此,催化剂的再生性能对烯烃裂解技术至关重要。在实验室对中国石化中原石油化工有限责任公司烯烃裂解工业装置的ZSM-5催化剂进行了多次反应和再生试验,考察其烯烃裂解反应性能,并运用TG、XRD、NH₃-TPD、氮气物理吸附以及SEM等对再生前后的催化剂样品进行表征。结果表明,开发的烯烃裂解催化剂经过13次的反应再生过程,新鲜催化剂与再生催化剂的比表面积和孔容基本相同,烯烃转化率、丙烯及乙烯收率无明显变化,烯烃转化率仍大于73%,丙烯和乙烯收率分别大于32%和10%。且催化剂骨架结构和酸中心稳定,在多次反应与再生过程中的酸量保持不变,具有良好的再生性能。     

CDOS催化剂的重油裂化性能

通过对某炼油厂减四线油和减四线抽出油的性能对比,选择更难裂化的减四线抽出油在小型固定流化床装置上,对以DOSY为活性组元的CDOS催化剂和常规REY重油裂化降烯烃催化剂进行对比实验,考察已工业应用的CDOS催化剂在实验室条件下,对催化剂的重油转化及降烯烃的能力。结果表明,在相同剂油比下,CDOS催化剂作催化材料时,具有更好的产物分布,可获得较高的转化率和轻质油收率以及较低的焦炭和重油收率。CDOS催化剂降低汽油中烯烃的能力高于常规REY类型重油裂化降烯烃催化剂。     

裂化催化剂失活动力学及平衡催化剂活性模型

基于催化剂全混流流动状态和呈指数形式的催化剂年龄概率密度函数,经催化剂失活动力学方程推导,确定了关联催化剂碳含量、金属沉积量、催化剂置换率、再生器温度和水蒸气分压的平衡催化剂活性或微反活性模型方程。对工业催化裂化装置操作数据进行模拟计算,确定了催化剂失活模型参数,建立了具有较高模拟计算精度的裂化催化剂失活动力学和平衡催化剂活性模型。比较模型参数大小可知,V沉积对催化剂活性的影响最大,其次是Ni和Fe,Na的影响最小。模型预测结果表明,随着平衡催化剂金属沉积量或碳含量减少,催化剂单耗增大,平衡催化剂活性或微反活性逐渐增大。适当降低再生器温度和催化剂藏量有利于提高平衡催化剂活性。     

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.     

Modelling the kinetics of fast catalytic cracking reactions

Instantaneous kinetic constants and gasoline selectivities have been determined for catalytic cracking of n-hexadecane. The pulse technique was used in order to model the sequential build-up of coke which occurs on cracking catalyst within a riser transport-line reactor. The total amount of hydrocarbon injected per unit weight of catalyst was between 0 and 10. The mathematical model used to analyze the data was based on the unsteady state mass balance of the microcatalytic reactor with the assumption of plug flow. Results suggest a fast deactivation process during the run with fresh catalyst, while regenerated catalyst showed a slower deactivation. The catalyst regenerated three times evidenced a low apparent activation energy when temperature was increased from 500°C to 550°C.     

Experimental investigation of the catalytic cracking of methane over a supported Ni catalyst

TGA experiments on the catalytic cracking of methane and methane diluted with hydrogen over a 5 wt% Ni/γ‐alumina catalyst at 500°C and 1 and 10 bar are described. Carbon deposition on the catalyst, as expressed in specific weight of carbon, varies with time. Eventually, the deposition stops because of deactivation. The specific weight at this point depends on the hydrogen partial pressure and there is also a weak dependence on the degree of contact between catalyst particles. A model based on assuming carbon deposition proceeds through whisker formation and growth, and deactivation occurs through encapsulation adequately describes the experimental observations up to 20 vol% hydrogen in the feed.     

催化裂化催化剂抗重金属技术应用与进展

简述催化裂化原料油中镍、钒、铁、钙、钠等重金属对催化裂化催化剂选择性和活性的影响,介绍抗镍、抗钒、抗铁和其他重金属技术的应用和进展,为新型抗重金属催化裂化催化剂的研究和发展提供思路。     

氧化物催化剂上石脑油催化裂解制乙烯的研究

使用固定流化床,考察了氧化物催化剂催化裂解石脑油制乙烯的反应。研究结果表明,温度、空速和水油比对裂解产物分布有直接影响。在反应温度700 ℃、空速0.75 h^－1和水油质量比3∶1条件下,得到最大的乙烯收率为32.93%。     

催化剂再生尾气中二氧化碳分析

介绍了一种定量分析气相氟化催化剂再生处理尾气中 (含氟化氢、氯化氢等酸性气体 )二氧化碳含量的化学方法 ,来判断催化剂再生进行的程度 ,从而决定催化剂再生处理的时间。此方法简洁、快速、实用、设备简单且不受尾气中腐蚀性气体的影响     

LV-23BC催化剂在渣油FCC装置上的应用

本文介绍了LV-23BC催化剂在庆化炼油厂Ⅱ套催化裂化装置上工业应用情况及使用效果。结果表明，LV-23BC具有良好的抗金属污染及渣油裂化能力、焦炭选择性和液化气选择性较高、催化剂单耗低、稳定性好等特点。     

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。     

Four-lump kinetic model for fluid catalytic cracking process

In the fluid catalytic cracking reactor heavy gas oil is cracked into more valuable lighter hydrocarbon products. The reactor input is a mixture of hydrocarbons which makes the reaction kinetics very complicated due to the involved reactions. In this paper, a four-lump model is proposed to describe the process. This model is different from others mainly in that the deposition rate of coke on catalyst can be predicted from gas oil conversion and isolated from the C₁–C₄ gas yield. This is important since coke supplies heat required for endothermic reactions occurring in the reactor. By this model we can also conclude that the C1–C4 gas yield increases with increasing reactor temperature, while production of gasoline and coke decreases.     

生物质油精制中失活催化剂的再生及焦炭前驱物分析

为了获得高质量生物质燃料油,需要对生物质直接裂解得到的生物质油进行催化裂解精制;精制过程中催化剂容易结焦,对精制反应产生很大影响.今采用热重,红外,核磁等分析手段,对生物质油催化裂解精制中所使用的催化剂HZSM-5上的焦炭前驱物进行了表征,从而对焦炭的生成以及催化剂再生进行深入研究.结果表明沉积在催化剂表面上的焦炭前驱物主要是短链饱和烃类化合物,沸点在200℃以下;催化剂内部的结焦前驱物主要为芳香族碳氢化合物,这些化合物的沸程范围在350～650℃.此外还对催化剂HZSM-5采用在空气中600℃焙烧的方式再生以及再生次数对产物量和催化活性的影响进行了研究.结果表明:再生前三次,催化剂活性变化不大,随着再生次数的增加,催化剂活性受到影响程度也增大.     

再生温度对FC-28型催化剂再生效果的影响

采用器外再生方法对工业失活的FC-28型催化剂进行再生,在不同再生温度制备系列催化剂,并利用TG、IR、XRD和TEM等手段考察再生温度对FC-28型加氢裂化催化剂再生效果的影响。结果表明,再生温度450 ℃时,失活催化剂可以烧掉绝大部分硫碳,金属元素基本得以恢复;催化剂表面酸性、催化剂比表面积和孔体积恢复到最大值。再生温度超过450 ℃时,开始出现少量的金属聚集,酸性降低,孔结构也不再恢复,适宜的再生温度才能使催化剂再生达到最好的效果。     

催化裂化催化剂磨损指数分析方法

对催化裂化催化剂磨损指数测定方法进行研究,通过实验优化测定催化剂磨损指数的预处理条件,考察焙烧温度和焙烧时间、催化剂用量、气体流速、纸筒对磨损指数的影响。结果表明,催化剂焙烧温度650 ℃,焙烧时间1 h,催化剂用量10 g,气体流速21 L·min^-1,选择纸筒时系统压力不超过30 kPa。催化剂磨损指数绝对偏差最大值0.16%,最小值0,准确度较高。催化剂磨损指数相对标准偏差低于5%,重复性较好。     

长链烷烃脱氢失活催化剂的表征及其烧炭再生温度研究

以N2物理吸附-脱附、压汞、热重和CO脉冲化学吸附催化剂物化表征手段对工业失活长链烷烃脱氢催化剂进行表征,并考察烧炭再生温度对催化剂活性的影响.结果表明,与新鲜催化剂相比,失活催化剂比表面积和总孔容略有下降,孔径分布向小孔方向移动.通过氧化烧炭可使催化剂活性部分恢复.O2-N2混合气(O2体积分数1%)气氛氧化烧炭适宜...     

丙烷脱氢制丙烯催化剂烧焦过程的模型化

在丙烷脱氢制丙烯反应过程中,由于焦的沉积使催化剂活性不断降低,而且失活速度很快,催化剂需频繁烧焦再生。在研究了丙烷脱氢催化剂烧焦过程内外扩散影响的基础上,采用内扩散效率因子修正的均匀烧焦物理模型,建立了综合考虑内外扩散影响的绝热固定床非均相动态烧焦数学模型,用于指导反应器的设计和操作优化。通过对Cr₂O₃/Al₂O₃脱氢催化剂烧焦过程模拟,可更深入地认识烧焦过程的变化规律。