| Along with the rapid development of industrialization and motorization,the gradual depletion of oil resources has become one of the most serious problems in the world.The replacment of fossil energy by renewable energy would ease the energy crisis and reduce CO2emission.Therefore,the strategy of producing jet fuel from biomass to has become a research focus recently.The advantages on low pollution and circular economy are in evidence.In this paper,H-ZSM-22 and H-ZSM-35 molecular sieve are selected as carriers.Bifunctional catalysts were prepared by modified carriers with Pt loading.The performance of these catalysts on hydrocracking and hydroisomerization for producing bio-jet fuel were investigated.The main research contents and results are as follows:?1?The performance of Pt/ZSM-22 prepared by modified H-ZSM-22 was investigated.The results showed that the catalyst was phosphated after passivation in water,which can significantly improve the selectivity of bio jet fuel from 29.6%to 55.7%.With phosphorus loading increasing,the pores of the catalyst will be further modified lead to increasing of the selectivity of paraffins(i-C16 and i-C17);The activity of catalysts and selectivity of bio-jet fuel were improved with the increase of Pt loading.The conversion and yield reach 97.2%and52.5%,respectively,the iso/n-paraffin ratio is 4.1.when the loading is 0.3%.The reduction of catalyst size is beneficial to increase the yield of bio-jet fuel.The reaction process conditions were optimized.The optimal reaction conditions are:295?,2 MPa,1 h-1,H2/n-paraffins volume ratio is 930:1.Under these conditions,reaction conversion rate reaches 96.3%,the yield and iso/n-paraffin ratio of bio-jet fuel are 59.1%and 4.1,respectively.?2?The long-term operation stability evaluation of Pt/ZSM-22 showed that the conversion of the reaction can still maintained above 90%after the continuous reaction of the catalyst for2000 h,indicating that the catalyst exhibited high activity and stability.To meet the conditions for further pilot scale-up,the catalyst was scaled up from the 2 mL device to the 100 mL device and then to the 1 L device.The results showed that:The catalyst showed excellent catalytic performance at different reaction scales.The yield of bio-jet fuel can reach 56.9%.?3?The reaction performance of H-ZSM-35 molecular sieve with different Si/Al ratio?10,15,20?on hydrocracking and hydroisomerization of long-chain normal bio-paraffins to bio-jet fuel were investigated.In this basis,the performance of catalysts prepared with loading of different precious metals and different platinum sources using H-ZSM-35?10?as catalyst carrier were evaluated.The study found that H-ZSM-35?10?show high selectivity of bio-jet fuel?52.4%?.The reaction performance of Pt/ZSM-35 was better than that of Pd/ZSM-35.Pt/ZSM-35 prepared by chloroplatinic acid as a platinum source possessed a higher activity due to have a stronger acidity,which will lead to the occurrence of deep cracking,reducing yield of bio jet fuel.?4?A series of bifunctional catalysts Pt/ZSM-35 with low platinum loading?0.1%,0.2%,0.3%?were prepared.The performance of Pt/ZSM-35 catalysts on the hydrocracking and hydroisomerization to bio-jet fuel was evaluated by the conversion of long-chain normal bio-paraffins,the selectivity of C9-C166 products,the yield and the iso/n-paraffin ratio of bio-jet fuel.Then the reaction process conditions were optimized.The results showed that The Pt/ZSM-35 catalysts with Pt loading of 0.1%-0.3%from platinum nitrate solution exhibited high activity and high selectivity with improved iso/n-paraffin ratio of bio-jet fuel.The optimized reaction conditions were obtained under 320?,1 MPa,0.7 h-1 with H2/n-paraffin volume ratio of 840:1.The conversion of long-chain normal bio-paraffins over0.1%Pt/ZSM-35 catalyst reached 84.3%,the yield of bio-jet fuel was as high as 41.0%with iso/n-paraffin ratio of 1.34.In the long term operation test for 81 h,0.1%Pt/ZSM-35 catalyst showed good stability. |
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