Synthesis Of Zeolite Using Spent Fluid Catalytic Cracking (FCC) Catalysts

Fluid Catalytic Cracking（FCC）constitutes a pivotal technology within the petroleum refining sector.Its fundamental principle involves the conversion of heavy petroleum fractions into higher-value light hydrocarbon products such as gasoline,liquefied petroleum gas,and light wax,facilitated by catalysts.Over time,FCC catalysts become progressively deactivated due to the influence of factors such as high temperatures,elevated pressures,acidity,and metal poisoning.These spent catalysts need to be regularly removed,generating a significant amount of waste catalysts.In2016,the Chinese Ministry of Environmental Protection categorized spent FCC catalysts as hazardous waste,imposing the requirement for their management in strict accordance with hazardous solid waste disposal regulations.Consequently,in alignment with national solid waste management policies and reduce the negative impact of solid waste on soil,water bodies,and air,there is an urgent imperative to advance technologies for the high-value utilization of spent catalysts.Zeolite,as significant aluminosilicate porous crystalline materials,find extensive application across diverse domains,encompassing petroleum refining,chemical industry,environmental conservation,wastewater treatment,separation technology,pharmaceuticals,life sciences,energy storage,and more.Importantly,the chemical composition of spent FCC catalysts closely corresponds with that of zeolite.Hence,zeolite emerge as an ideal target for the high-value utilization of spent FCC catalysts.However,the prevailing methodologies for synthesizing zeolite materials from spent FCC catalysts predominantly rely on intricate pre-treatment processes.To actualize the industrial-scale production of zeolite derived from spent FCC catalysts,it becomes imperative to streamline the pre-treatment procedure,elevate product quality,and broaden the spectrum of potential applications.This study delineates the development of a novel,streamlined pre-treatment process for waste catalysts and the synthesis of diverse zeolite.Thorough investigations were undertaken regarding the conversion process of solid waste and the crystallization process of molecular sieves.Distinct evaluation frameworks were established for various molecular sieve types,encompassing assessments of ion exchange capabilities,gas adsorption and separation characteristics,and catalytic performance.On the basis of these evaluations,the manufacturing processes for high-performance zeolites were systematically upscaled to volumes ranging from 100 L to 1000 L.The principal research contributions of this paper are elucidated as follows:1.An innovative low-temperature alkali fusion pre-treatment methodology was pioneered,resulting in the successful synthesis of zeolite X.The degree of material disaggregation during the pre-treatment process was found to be intricately linked to the final crystalline phase of the product.The synthesized zeolite X were subjected to stringent testing in accordance with the national standard GB 6287-86,achieving a static water adsorption capacity of 32.11%.Furthermore,the intricate impact of variations in the formulation’s constituent components on the resulting products was meticulously examined,with a concurrent tracking of the crystallization process of the zeolite.Combining static single-component gas tests and dynamic breakthrough experiments,the CO₂ separation efficiency of zeolite X was systematically explored,unveiling their remarkable aptitude for efficient CO₂ separation within binary gas mixtures,such as CO₂/N₂ and CO₂/CH₄.2.Building upon the preceding research,a method for synthesizing LTA zeolite from spent FCC catalysts was successfully developed.Solid-state nuclear magnetic resonance techniques were employed to monitor transformations in species during the pre-treatment steps.The derived LTA zeolite exhibited elevated static water adsorption capabilities（26.71%）,surpassing the first-grade product standards stipulated in GB6287-86.The adsorption behavior of LTA zeolite towards Co²⁺ions in wastewater was comprehensively investigated.To ascertain the universal applicability of this synthesis method,experiments were conducted utilizing lithium ore slag as a substitute for FCC waste catalysts.Under refined formulation conditions,LTA zeolites were successfully generated,with a systematic exploration of their adsorption behavior for Sr²⁺in wastewater.Moreover,the synthesis of LTA zeolite from FCC waste catalysts was scaled up in a 100 L reactor.3.A pioneering method for the direct synthesis of MOR zeolite from spent FCC catalysts,obviating the need for pre-treatment steps,was devised.Comprehensive scrutiny of the physicochemical properties of zeolite and the influence of various constituents in the initial gel on crystallization products was conducted.In-depth analysis of the crystallization kinetics and phase transformation process of MOR zeolite was performed,along with an investigation into the presence of metal elements from spent FCC catalysts in the resulting MOR zeolite.The obtained MOR zeolite exhibited a unique capacity for precise CO₂ separation in a variety of gases,distinct from conventional MOR zeolite.Elaborate exploration of CO₂ adsorption kinetics and thermodynamic properties on MOR zeolite was undertaken.Fixed-bed breakthrough experiments encompassing binary gases,quaternary gases,and an eight-component mixed gas simulating refinery dry gas were conducted to affirm the dynamic separation capabilities of MOR zeolite.The synthesis methodology was successfully scaled up in a 1000 L reactor.4.In addition to the aforementioned zeolite,several other molecular sieves were synthesized from spent FCC catalysts under conventional hydrothermal conditions.Low-silica ZSM-5 zeolite was successfully synthesized without the use of templates.High-silica CHA zeolite was synthesized employing TMAda OH as a template agent,and high-silica ZSM-5 zeolite was synthesized employing TPAOH as a template agent.The influence of various components in the formulation and crystallization conditions on the resultant products was scrutinized through batch experiments.Among these,the synthesis of low-silica ZSM-5 zeolite was successfully scaled up in a 100 L reactor.