Hydrodeoxygenation Of Fatty Acid Methyl Esters And Isomerization Of Products Over The Catalysts With SAPO-11 As Carrier

In this paper,the fatty acid methyl ester(FAME)was used as the model of the waste oil.The catalysts consisted of the carrier of molecular sieve SAPO-11 and the active components of nickel-phosphorus compounds.Catalysts with various nickel loading,nickel-phosphorus ratio and different molybdenum loading were prepared by carrier extrusion,sieving and over-impregnation.Their physical and chemical properties were tested and analyzed by means of pyridine infrared spectroscopy?NH3-TPD?SEM?EDS?H2-TPR?N2 adsorption-desorption?elemental and thermogravimetric analysis.The catalytic performances for hydrodeoxygenation of FAME and consecutive isomerization of paraffin products were carried out in a trickle-bed continuous-flow reactor.Liquid products were qualitatively and quantitatively identified by GC-MS and GC,respectively.(1)By the characterization of the three groups catalyst precursors,it was found that the skeleton structure of SAPO-11 carrier in catalysts were maintained.BET data showed that those catalyst precursors were meso-porous with the average pore size between 2 and 50 nm and displayed typical isothermal adsorption lines(IV).The reduction temperature of nickel oxide was about 450 ?,and molybdenum oxide and the phosphorous oxides of nickel 550-700 ?.At the same time,there existed B acid sites in the three groups of catalysts,but the amount of acid varied with the loading.SEM and EDS results confirmed that the carriers in the catalysts exibited rectangular block structure.After the carriers formed,crushed and impregnated,their structures were slightly damaged while the general structure remained.(2)By single factor experiment,catalytic performance of the catalysts with different nickel loading,nickel/phosphorus mole ratio and molybdenum loading were tested to find the optimal catalyst.The catalyst loading was 1.0 g.The reduction reaction conditions of catalyst precursors were as follows:temperature 650 ?,hydrogen flow rate 320 mL/min,H2 pressure 1.0 MPa,reduction time 3 h.The catalytic hydrodeoxygenation and consecutive isomerization of paraffin products reaction conditions were as follows:WHSV 2.5 h-1,H2 pressure 2.0 MPa,temperature 340 ? and the hydrogen flow rate 60 mL/min.The analysis results of liquid products showed that the 3wt%NiP(3/2)/SAPO-1 1 catalyst achieved relatively high isomerization rate(14.10%),C15-18 yield(88.60%)and FAME conversion(98.45%).(3)As to the 3wt%NiP(3/2)/SAPO-11 catalyst,the effects of reaction temperature,pressure and WHSV on the catalytic performance of the catalysts were investigated by single factor experiments.The optimum operating conditions were gained as follows:WHSV 2.5 h-1,H2 pressure 1.5 MPa,temperature 360 ? and the hydrogen flow rate was 60 mL/min.Correspondingly,the raw material conversion rate retained 98.36%,the yield of C15-18 94.60%,the isomerization rate 59.36%.(4)Through the stability test of the 3wt%NiP(3/2)/SAPO-11 catalyst,the conversion of raw material and the yield of C15-18 changed slightly with the running time,while the product isomerization rate decreased sharply.