Bifunctional Catalyst For Heavy Oil Catalytic Cracking And Gasification Regeneration Coupling Process

Petroleum resources are becoming more degraded,heavier and high proportion with the diminishing of the world conventional oil reserves.As a result,processing these inferior oil feedstock will be inevitable generated a large amount of petroleum residues?such as,vacuum residue,atmospheric residue,deoiled asphalt and oil slurry?and the petroleum coke products.It is generally known that there are two types of technical routes to process these petroleum residues,which is decarbonization and hydrogenation,respectively.The residues Fluidized catalytic technology,as a decarbonization process,has been widely applied for processing the petroleum residues in the refineries.Nevertheless,this technical would lead to the catalysts rapid loss its activity and acquire low heavy oil conversion,when processing the high-sulfur and heavy metal content petroleum oil feedstocks.The heavy residues hydrogenation process usually requires the condition of the H₂-rich atmosphere and high pressure,and leading to relatively high plant investment and the operation cost.Considering the deficiencies of the existing heavy oil processing technology,a new processing technology of heavy oil catalytic cracking and the gasfication regeneration process is carried out to realize the hierarchical and value-added conversion of the petroleum residues.In this process,heavy oil was first reacted with the base catalysts in a fluidized bed reactor to produce light olefins and light oil products.Subsequently,the spent catalysts were regenerated in this fluidized bed reactor for the catalyst gasification regeneration.And then the H₂-rich syngas and the regenerated catalysts could be produced.Furthermore,the regenerated catalysts were circulated in this fluidized bed reator,which could provide the reaction heat and catalysis for the heavy oil conversion.Fundamental studies on catalytic cracking and gasification regeneration bifunctional catalysts are carried forward for the heavy oil catalytic cracking and gasification regeneration coupling process and the main conclusions are listed as follows:1?Catalytic cracking behaviors of heavy oil over different catalysts were studied in a fluidized bed reactor,in terms of determining the kind of catalyst.The results show that silica sand?the absence of catalytic activity?or FCC catalyst?high catalytic activity?could not meet demands for the heavy oil feedstock conversion,and meanwhile acquired the higher olefins and light liquid oil yield.Calcium aluminate catalyst not only had moderate catalytic activity,inhibit the formation of coke and high heavy oil conversion,but also could realize to gain the products of low carbon olefins and light liquid oil with a higher yield.Furthermore,the coke over the base catalysts could be well gasified,and co-producing the H₂-rich syngas.Calcium aluminate catalyst showed the bifunctional characteristics of heavy oil cracking and the coke catalytic gasification,and this manifested the feasibility of its utilization for petroleum residue cracking gasification.Moreover,the industry calcium alumina catalyst and self-made calcium alumina catalysts?the Ca/Al molar ratio of 12:7?exhibited the good cracking performance of heavy oil feedstock with the condition of reaction temperature 700 ^oC,the steam/oil mass ratio and the catalyst/oil mass ratio of 1.0 and 7.0,respectively.2?On the basis of confirming the type,reaction condition and calcium/aluminum ratio of cracking catalyst,and meanwhile the texture properties of the catalyst was optimized.The results showed that calcium alumina catalysts exhibited good texture properties and crystal morphology,when using carbon black as hard template,CaCO₃ and Al₂O₃ as raw material,and calcination temperature of 1350 ^oC.Different specific surface area and hydrothermally treated calcium alumina catalysts were investigated with the purpose of studying the cracking performance of the heavy oil feedstock conversion.It was found that calcium alumina catalyst with higher specific surface area displayed a better cracking performance than the one with lower specific surface area.Furthermore,the C2?C4 olefinicity in the cracking gas of higher than 65.0%,and carbon deposited of ca.5.2 wt%are achieved by cracking at 650 ^oC with a catalyst-to-oil ratio 7.0.The cracking activity of the hydrothermal treatment calcium alumina catalyst could reach basically stable in the heavy oil catalytic cracking process.The coke on the catalysts is well gasified at 800 ^oC in steam-5.0 vol%oxygen.The H₂ content and H₂/CO ratio are separated reached about 58.0 vol%and 4.5,with the CH₄ content less than 0.5 vol%.Also,the catalytic cracking performances of calcium alumina catalyst could reach basically stable via a few cracking gasification cycles.3?In order to realize the distribution of heavy oil cracking products could be adjusted,manganese nitrate or potassium permanganate were chosen to modify the calcium aluminate catalyst.The study found that the manganese nitrate modified calcium aluminate catalyst had better cracking products adjustment ability than potassium permanganate modified calcium aluminate catalysts.The results showed that the Mn-modified catalysts showed proper heavy oil cracking activity to allow both the liquid yields of about 65 wt%and heavy oil conversion ratio of up to 92.0%at 650 ^oC with the catalyst-to-oil of 7.0.In comparsion with the C2?C4olefinicity of 63.4%and the C4?C5 yield of 3.0 wt%over the unmodified calcium aluminate catalysts.The manganese nitrate modified calcium aluminate catalysts had better cracking products adjustment ability.Namely,the C2-C4 olefinicity of 0.4 wt%-Mn/C₁₂A₇ catalysts is increased to 66.9%and the C4?C5 yield has changed little,while C2-C4 olefinicity of the 1.0wt%-Mn/C₁₂A₇ and 2.0 wt%-Mn/C₁₂A₇ catalysts is decreased to 40.1%and 25.1%separated,and meanwhile the yield of C4?C5 increased to 11.5 wt%.And then the cracking products adjustment could be realized.The coke over the modified calcium aluminate catalyst could be gasified well in a gasification reagent of steam,resulted in the syngas products containing the H₂ and CO₂ content to be about 58.0 and 24.0 vol%,respectively,with the CH₄ content less than 0.8 vol%.Also,it is also verified the possibility of circulating the potassium manganite modified calcium aluminate catalysts in vacuum residue cracking gasification process.4?The spent base catalysts optimum gasification conditions,gsification reagent ratio and time were tested in a fixed bed reactor and high temperature water vapor heat analyzer.In turn,the results could provide the guidance for the spent base catalysts fluidized gasification reaction and industrial applications.The results show that the gasification reaction rate of the coke on the calcium aluminate catalyst varies directly as the gasification reaction temperature.Moreover,it was also found the initial gasification temperature of the coke is about at 680 ^oC.The gasification reaction time is about 30 min could achieve a good conversion of coke on the calcium aluminate catalysts.The catalysts particle size is above 100?120 mesh,which could basically eliminate the performance of the internal and external diffusion on the coke catalytic gasification reaction.Steam/oxygen gasification reagent is used in the gasification reaction,which could obviously improve the conversion rate of the coke,and meanwhile affect the composition of synthesis gas.5?According to the gasification performances study of different types of petroleum coke?pure petroleum coke,petroleum coke mixed with alkaline reagents and petroleum coke impegnated with alkaline reagents?.A new type of carbon-water vapor catalytic gasification reaction theory is proposed based on the water vapor dissociation mechanism.The theory is that the water dissociation to produce·OH radicals can promote the petroleum coke catalytic gasification reaction,and reducing petroleum coke initial gasification reaction temperature and improving gasification reaction rate.Thus,the gasification reaction ratio of petroleum coke and steam is related to the concentration of the·OH radicals in the gas phase of the reaction system.