| The GC-MS method for industrial dipentene chemical composition analysis was developed,and the there industrial dipentene's composition characteristics were deteminated.Dipentene reaction was catalyzed by several kinds of zirconia solid acid catalyst,and the p-cymene relative content in the products was detemianted and compared for select the suitable catalyst.The dipentene reaction process was studied,which was catalyzed by different kinds of SO42-/ZrO2 solid acid catalyst,and the influence of reation time and reation temperature on the p-cymene relative content.The main results as follow:1.Analysis of the industrial dipentene chemical compositionThe three industrial dipentene samples' compositions were similar.There are the same 9 compositions in the three samples,such as dipentene,terpinalene,a-terpinene and p-cymene and so on.The sum of the mass fraction of the same 9 components in industrial dipentene A(byproduct of the camphor production process),B(byproduct of the terpineol production process)and C(byproduct of the Fir essential oil production process)reached 86.10%,60.87%and 49.08%,respectively.Addition to monoterpenoids,industrial dipentene B was also rich in Eucalyptol,and industrial dipentene C had higher content of open loop terpenes and aromatic compound,and its components were more complex.The chemical composition difference between the three industrial dipentene was obvious,depending on the source of raw materials.Industrial dipentene A and B contaned more same components because of that it were the byproduct of turpentine oil processing.While industrial dipentene C came from the byproduct of Fir essential oils,and its main composition showed significant specificity.However,their main components distribution was relatively concentrated,especially that the sum of relative mass fraction which greater than 10%in the industrial dipentene A reached 67.23%,so it was practical significantly to utilize the components.2.SO42-/ZrO2 solid acid catalyst preparation and catalyst selectionComparing to solid acid catalytic 1#(S2O82/ZrO2-TiO2,the titanium dioxide derived from TiCl4),5#(S2O82-/ZrO2-TiO2,the titanium dioxide derived from titanium powder)and 7#(S2O82-/ZrO2),SO42-/ZrO2 solid acid catalyst had better catalytic effect on the dipentene synthesizing p-cymene reaction,with fewer byproducts and higher relative content of the target compound.3.The reaction of dipentene catalyzed by SO42-/ZrO2 solid acid catalystWithin 10 min to 15 min,the reaction system exotherm strongly,and the reaction speed is very quickly.It showed that the reaction mainly happened in this period of time,and SO42-/ZrO2 solid acid catalysts appeared a high activity for the reaction.The reaction products included monocyclic monoterpene,p-cymene and dehydrogenation substance.The entire reaction system mainly contained isomerization and disproportionation.Under the effect of SO42-/ZrO2 solid acid catalyst,dipentene isomerismed and rearranged into monocyclic monoterpene,then dehydrogenated into p-cymene that chemical structure was stable,which was the main reaction.Meanwhile,dipentene and monocyclic monoterpene absorbed the hydrogen that departed from the main reaction process generating p-menthene and carane.As the reaction continued,the monocyclic monoterpene content of the profuct decreased gradually.The influence of the temperature the dipentene' conversion rate is small,but it affected p-cymene' content greater.With extension of time,the conversion rate of dipentene and p-cymene' content was slowly increased,rapidly,in 10min to 15min.Then their increase in amplitude was slightly smaller,and gradually became constant.the conversion rate of dipentene could reach 100%,and p-cymene' content could 44.91%(140?). |
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