摘要
利用有限的石油资源生产高附加值化工原料(低碳烯烃与芳烃)是石油资源低碳高效利用的重要途径。基于我国的能源结构和在催化裂化领域的技术优势,重质原料油在分子筛限域催化下裂解直接制低碳烯烃与芳烃是我国炼油产业的重要发展方向。这对涉及分子筛内离散传递、吸附与反应等过程的调控和多相反应器的设计提出了挑战:(1)分子筛内大分子及芳烃的强吸附对低碳烯烃的传递造成较大的阻力,要求高剂油比及逆流接触,防止重质芳烃的优先吸附并实现低碳烯烃的深度裂解;(2)二次反应速度比一次反应快,要求毫秒级接触时间和近平推流的停留时间分布方可得到高的中间化学品收率。解决这些问题需要在催化剂及反应器两方面同时改进。在这个背景下,本文重点介绍了重质油催化裂化直接制化工品中的离散传递、反应与失活过程,以及气固多相反应工程等相关领域的进展,分析了小分子在分子筛中吸附扩散和相关主客体相互作用研究的最新工作,提出应使用具有晶面选择性的抗积炭高活性纳米分子筛和气固逆流接触的平推流反应器。最后介绍了清华大学自主研发的多级逆流下行催化裂解技术(multi-stage downer catalytic pyrolysis,MDCP^(TM))——通过毫秒级平推流的多级气固并流顺重力下行反应器,级间油气与催化剂逆流接触,大大提高了乙烯、丙烯收率,并减少柴油、油浆收率。1 kg/h的全流程实验结果表明MDCP^(TM)单程双烯收率高达51.54%(质量分数,下同),且汽油中单环芳烃选择性可达80.78%。以MDCP^(TM)为核心单元的重质油直接制化工品(heavyoilto chemicals,HOTC)工艺路线可以得到大于75%的综合化工品收率,与现有技术相比可以降低70%以上的碳排放。
High yield of petrochemicals,such as light olefins and aromatics,is an important way for low-carbon utilization of petroleum.Based on China’s energy structure and technological advantages in the field of catalytic cracking,the direct production of light olefins and aromatics from heavy feedstock oil under the confinement of molecular sieves is an important development direction of China’s oil refining industry.It poses great challenges to the design of multi-phase reactors.Counter-current interaction between feed-oil and deep-cracking catalysts under high severity should be achieved to prevent preferential adsorption of heavy aromatics,reduce diffusion resistance in zeolitic nanopores,and boost deep cracking of short-chain alkanes.Millisecond residence time and plug-flow residence time distribution should be obtained to inhibit secondary reactions and reduce dry gas and coke production.This review focuses on the progress of discrete transport,reaction,and deactivation processes in the catalytic cracking of heavy oil directly to chemicals,as well as the progress of gas-solid heterogeneous reaction engineering and other related fields.The latest research work on the discrete adsorption-diffusion phenomenon and host-guest interactions of small molecules in zeolites are introduced,and it is proposed to use facet-selective nanosized zeolites with high resistance to coke formation and gas-solid counter-current contact plug flow reactors to overcome the above challenges.Finally,the multi-stage downer catalytic pyrolysis(MDCP^(TM))developed by Tsinghua University is introduced,which uses multi-stage downers in series while achieving both millisecond-level plug-flow within one stage and counter-current gas-solids interaction between each stage.In the 1 kg/h pilot plant,MDCP^(TM)can gain excellent production distribution[51.54%(mass)yield of light olefins and 80.78%(mass)selectivity of BTEX in gasoline].With MDCP^(TM)as the core unit,the process,i.e.,heavy oil to chemicals(HOTC),is reported where the yield of the total
作者
熊昊
梁潇予
张晨曦
白浩隆
范晓宇
魏飞
XIONG Hao;LIANG Xiaoyu;ZHANG Chenxi;BAI Haolong;FAN Xiaoyu;WEI Fei(Department of Chemical Engineering,Tsinghua University,Beijing 100084,China)
出处
《化工学报》
EI
CSCD
北大核心
2023年第1期86-104,共19页
CIESC Journal
基金
国家自然科学基金项目(22238004,22278238,22275110,22208186)。
关键词
多相流
沸石
流化催化裂化
多级下行床
逆流接触
重质油直接制化工品
multiphase flow
zeolite
fluidized catalytic cracking
multi-stage downer
counter-current interaction
heavy oil to chemicals
