Study On The Preparation Of ZnAPO-11 And La₂O₃/ZnAPO-11 And Their Catalysis In The Synthesis Of Borneol From Turpentine

Turpentine resources is rich in China and distributed widely,and its output ranks second in the world,but 80%of it was directly used as a product,which greatly reducing its utilization value.The main components of turpentine ar e?-pinene and?-pinene.These olefins are chemically active and can be synthesized into a variety of higher value products like borneol.The dragon brain was divided into the positive borneol and the isoborneol.The value of the borneol was much higher than that of the isoborneol.The?-pinene esterification-saponification synthesis method is one of the ways to prepare the borneol,and the product is mainly required to be the borneol.Therefore,the research and preparation of highly selective catalysts fo r the synthesis of borneol in turpentine is of great significance for the deep processing of turpentine to produce high value-added products.At present,the catalysts for the turpentine esterification-saponification reaction generally are boron,titanium,boron-titanium composite catalysts,solid superacids,heteroatom molecular sieves and rare earth compounds.Heteroatom molecular sieves are easy to control due to pore structure and surface acidity,simple preparation process and low equipment requirements,which have led to extensive research.Rare earth compounds are abundant in China and can effectively improve the esterification reaction activity,which has arouse many scholars'attention.In this thesis,the author prepared a heteroatom molecular siev e ZnAPO-11 and supported the rare earth compound as an active component on the support ZnAPO-11 to obtain a supported La₂O₃/ZnAPO-11 catalyst.ZnAPO-11 and La₂O₃/ZnAPO-11 were used as catalysts in the study of turpentine synthesis of borneol.The details a re as follows:?1?Heteroatom molecular sieves ZnAPO-11 were prepared by hydrothermal synthesis method.The suitable preparation conditions were determined by single factor experiments:initial gel mother liquor composition:n?R?:n?ZnO?:n?Al ₂O₃?:n?P₂O₅?:n?H₂O?=4:0.05:0.975:1.1:70,the crystallization temperature was 200°C,24h for the crystallization,and the reproducibility was well.It was used to catalyze the esterification of turpentine.The process conditions were optimized by single factor experiment and orthogonal experiment.The suitable process conditions for esterification of turpentine oil are as follows:reaction temperature 80°C,7h for reaction,catalyst dosage 7wt%,esterification agent dosage.The amount of the raw material conversion was 100%,the borneol selectivity was 58.84%,a nd the product m?positive?/m?total?was 90.00%.The reproducibility under this condition was well;the catalyst life test showed that the catalyst was effectively used 5 times.?2?A supported La₂O₃/ZnAPO-11 catalysts were prepared by ion exchange method.The suitable preparation conditions for the catalyst were determined by single factor experiments:m?La₂O₃?/m?ZnAPO-11?was 0.18,system pH was 9,preparation temperature was 30°C,30min for preparation time,calcination temperature was 450°C,3h for roasting.The catalyst preparation conditions were correlated with the catalyst performance.La₂O₃/ZnAPO-11 was used in the reaction of turpentine esterification-saponification synthesis of borneol.The process conditions were optimized by single factor experiment and orthogonal experiment.The suitable process conditions were as follows:reaction temperature 70°C,reaction time 7 h,catalyst The dosage was 7 wt%,and the amount of the esterifying agent was 0.4 mol;under this condition,the conversion of the raw material is 100%,the selectivity of the borneol was 66.72%,and the m?positive?/m?total?in the product was 93.77%.The reproducibility under this condition was well;it can be seen from the catalyst li fe test that the catalyst can be effectively used 5 times.?3?The above catalysts were characterized by XRD,BET,NH ₃-TPD,FT-IR,Py-IR,TG,SEM and other characterization methods.The results show that the heteroatomic molecular sieves and the supported catalyst were AEL topological structures;SEM showed that the morphology of the heteroatom molecular sieve was a cluster of long strips of crystallites,and the specific surfa ce area of ZnAPO-11 was119.23m²/g^-1.The capacity was 0.09 cm³/g,the average pore diameter was 3.12 nm,the specific surface area of the supported catalyst was 122.86m²/g^-1,the pore volume was0.14cm³/g,and the average pore diameter was 4.61nm;the NH₃-TPD pattern showed that the hetero atom molecular sieve h ad weak acidity and has a large amount of acid;FT-IR spectrum showed that Zn element successfully replaces part of Al of molecular sieve and enters the skeleton of molecular sieve;Py-IR spectrum showed that supported catalyst has acidity center of L acid and B acid;XPS map s howed load The active component in the type of catalyst was present as La₂O₃.ZnAPO-11 had weak acidity and large acid content.The supported La ₂O₃/ZnAPO-11 catalyst has both B acid center and L acid center,which were beneficial to the synthesis of borneo l by turpentine,and the content of borneol in the product was higher.