Design And Characterization Of Functionalized Sulfonic Supported Solid Acid Catalyst For Production Of Biodiesel

To solve the approach of energy crisis and aggravation of environmental pollution,biodiesel has been becoming an alternative energy in recent years for its remarkable advantages such as renewability,environmentally friendly and excellent combustion performance.The main production method of biodiesel is esterification,which is highly dependent on acid catalysts.The supported solid acid catalyst has become one of the important research directions for production of biodiesel because of its high designability,strong catalytic activity and high stability.The main preparation methods of supported solid acid include post-gifting method and impregnation method.In this work,a series of catalysts were prepared by optimizing the acid donor,carrier and loading method of the supported solid acid.After comparison,the functionalized sulfonic supported solid acid catalyst is considered as the ideal catalyst for production of biodiesel.Firstly,ZrO₂-TiO₂@HPW solid acid catalyst was prepared via impregnation method that phosphotungstic acid?HPW?was loaded on the surface of ZrO₂-TiO₂.After a series of experiment for optimzation,the optimal parameters were found.When the molar ratio of Zr/Ti was 2:1,the calcination temperature was 100°C,and the loading of phosphotungstic acid was50 wt.%,not only is catalytic activity of catalyst strong,but also catalyst is economical.Under the optimal parameters of preparation,ZrO₂-TiO₂@HPW nanorods were prepared by substituting ZrO₂-TiO₂ for ZrO₂-TiO₂ nanorods.After characterization of XRD,SEM,FT-IR,TBA,TGA and acid-base titration,both ZrO₂-TiO₂@HPW and ZrO₂-TiO₂@HPW nanorods were studied carefully.For further investigate catalytic performance,ZrO₂-TiO₂@HPW and ZrO₂-TiO₂@HPW nanorods were used to catalyze the esterification of palmitic acid and methanol.When the reaction temperature was 100°C,the amount of catalyst was 5 wt.%,MeOH/OA molar ratios was 20:1,and the reaction time was 5 h,the reactions of esterification,catalyzed by two solid acid respectively,reached high yields of 88.1%and 90.5%.However,the stability of the two catalysts is defective,after 5 times of reusing,their yields decreased to58.0%and 63%,respectively.On the basis of the previous research,two functionalized sulfonic solid acids,ZrO₂-TiO₂@SO₄^2-nanorods and ZrO₂-TiO₂-SO₃H nanorods,were prepared by the impregnation method and post-gifting method respectively.After characterization of XRD,SEM,FT-IR,Pyridine FT-IR,TBA,EDS,TGA,acid-base titration,the catalysts were studied carefully.For further investigation,the two sulfonic nanorods were used to catalyzed esterification of palmitic aicd.When the amount of catalyst was 5 wt.%,MeOH/OA molar ratios was 25:1,and the reaction time was 4 h,the esterification,catalyzed by ZrO₂-TiO₂@SO₄^2-nanorods,reached the highest yield of 95.3%.When the reaction temperature was 100°C,the amount of catalyst was5 wt.%,MeOH/OA molar ratios was 25:1,and the reaction time was 5 h,the esterification,catalyzed by ZrO₂-TiO₂-SO₃H nanorods,reached the highest yield of 93.1%.After 5 times of reusing,ZrO₂-TiO₂-SO₃H nanorods showed stable catalytic activity with the yield of 85.1%.However,the catalytic activity of ZrO₂-TiO₂@SO₄^2-nanorods is defective because its yield decreased to 53.8%.Finally,according to the previous research,it's found that the functionalized sulfonic acid supported solid acid,which is ideal catalyst for production of biodiesel,can be prepared by substitution reaction between silane coupling agent with-SH and carrier with abundant-OH,followed by oxidation and acidization.For further investigate this procedure,ZrP-SO₃H was prepared with the carrier of zirconium phosphate?ZrP?.As a comparison object,ZrP was treated by tetra-n-butylammonium hydroxide?TBA?for expand the interlayer spacing.Then modified zirconium phosphate?E-ZrP?was obtained as carrier.E-ZrP-SO₃H was prepared with same procedure.After characterization of SEM,TEM,X-ray,FT-IR,TGA,BET,the two solid acids were studied carefully.For further investigate their property,ZrP-SO₃H and E-ZrP-SO₃H were used to catalyzed esterification of palmitic acid.When MeOH/OA molar ratios was 30:1,the amount of catalyst was 5 wt.%,the reaction temperature was 90°C,and the reaction time was5 h,the esterification,catalyzed by ZrP-SO₃H,reached the highest yield of 94.7%.When MeOH/OA molar ratios was 30:1,the amount of catalyst was 5 wt.%,the reaction temperature was 90°C,and the reaction time was 4 h,the esterification,catalyzed by E-ZrP-SO₃H,reached the highest yield of 96.5%.Both show stong catalytic activities.After 5 times of reusing,the yields still up 86.6%and 90.0%respectively,which shows that both catalytic acitivies are stable.