Study Of The Hydrogenation Of ?-pinene Over The Ni-based Catalyst Modified With Ionic Liquid

Pinene is the most representative natural renewable biomass resources in terpenoids.The turpentine contains 58-65%of a-pinene and about 30%of?-pinene.Their chemical reactivity is very high,and a variety of chemical reactions can occur,such as hydrogenation of the pinene to pinnae,isomerization to form terpenes and so on.And there are two kinds of the products of the hydrogenation of a-pinene,cis-pinane and trans-pinane.Cis-pinane could synthesize various intermediates such as linalool?dioxymyrcenol?citronellol and rose ether.At present,in many studies,noble metal ruthenium is used as an active component to catalytic hydrogenation of a-pinene to prepare the cis-pinane,and it's catalytic activity and selectivity toward cis-pinane is very high.However,the price of the metal Ru is expensive,which will increase the industrial production cost.Transition metal nickel is often used in catalytic hydrogenation reactions,including Raney nickel,nano-nickel,supported nickel-based catalysts,amorphous nickel-based catalysts,and other element-doped nickel-based catalysts.Although the activity of the Ni-based catalysts is high,their selectivity to cis-pinane is not good as that of noble metal ruthenium catalysts.Ionic liquids,also known as room temperature ionic liquids or room temperature molten salts composed entirely of ions at or near room temperature.The ionic liquid can be used as a reaction solvent in the catalytic reaction,or the ionic liquid itself can be used as a catalyst for the reaction system,or as a modifier of the active component in the catalyst to play a synergistic catalytic role.The solid catalyst with an ionic liquid layer(SCILL).Since the iridium molecular layer ionic liquid film is only a few nanometers thick,the mass transfer heat transfer problem caused by the catalytic reaction can be ignored,it also greatly saves the use of ionic liquids and reduces the cost of industrial production.In this experiment,a post-treated deserted heavy oil fluid catalytic cracking catalyst(DF3C)was also used as a carrier for the catalyst.The content of this work is as follows:Preparation of N-(2-hydroxyethyl)-3-methylimidazolium tetrafluoroboron by two-step synthesis using N-methylimidazole,1-chloropropanol and sodium tetrafluoroborate as raw materials.Characterization analysis was carried out by 1H NMR and FT-IR.The DF3C supported nickel catalyst(Ni/DF3C)was prepared by an equal volume impregnation method and a temperature programmed reduction technique.The prepared nickel-based catalyst was subjected to equal volume impregnation with different ionic liquid content acetone solutions to prepare catalysts of different ionic liquid loadings(IL-Ni/DF3C).The catalyst was subjected to a series of characterization analysis by nitrogen adsorption desorption test,X-ray diffraction,scanning electron microscopy,Fourier infrared,X-ray photoelectron spectroscopy and other analytical methods.The nitrogen adsorption and desorption test showed that the specific surface area of the DF3C after calcination was greatly improved,indicating that there was a large amount of carbon deposit on the surface of the untreated DF3C catalyst;X-ray diffraction test indicated that DF3C was composed of SiO2,A1203,ZSM-5 and Y molecular sieves,while the coating of ionic liquids does not have a great influence on the crystal structure of the metal nickel.The structure of ionic liquid molecules was detected by Fourier infrared test.X-ray photoelectron spectroscopy indicated that the nickel-based catalyst modified by ionic liquid had a certain chemicalshift,indicating that there is a certain chemicalaction between the active sites and the ionic liquid.The application of IL-Ni/DF3C in the catalytic hydrogenation of a-pinene investigated the effects of different ionic liquid coatings on the activity and selectivity.At the conditions of 110??5.5 MPa and 135 min,the conversion could reach above 99%,and the selectivity for cis-pinane could reach above 98%.At the same time,we also explored the influence of temperature and hydrogen pressure on the conversion and selectivity.The increasing temperature and hydrogen pressure have a good effect on the reaction rate and conversion,but have little effect on the selectivity of the cis-pinane.The activity of the catalyst without ionic liquid was significantly reduced after repeated use for 4 times,and the catalytic activity of the catalyst modified with ionic liquid could keep high for 13 times.It indicates that the ionic liquid can improve the selectivity toward cis-pinane and also protect the active metal nickel from being oxidized by air and deactivated.We also used active carbon as a catalyst carrier,and prepared an active carbon-supported nickel-based catalyst.The catalysts were characterized by TEM?XRD?XPS and BET.Ni/C catalysts with different ionic liquid loadings were used for the catalytic hydrogenation of ?-pinene.The effects of different temperatures,hydrogen pressure and ionic liquid loading on the catalytic activity and selectivity were investigated.The test results were similar to that of DF3C.We tested the life of the catalyst,and there was little decrease in activity and selectivity for 11 runs.