Highly Dispersive Ni₂P Catalysts Prepared By Low Temperature Method For The Hydrogenation Of Petroleum Resins

Petroleum resin is produced by polymerization of C5/C9 fraction,which is the by-product in the ethylene unit.Petroleum resin is widely used in hot-melt adhesives,paints,inks,rubber and other fields.However,the raw material normally has yellow or amber color,poor thermal stability,poor oxidation resistance and other shortcomings,because of the high content of unsaturated bonds as well as sulfur and halogen residues.Catalytic hydrogenation is certainly the most widely applicable method for the improvement of petroleum resin quality.However,the difficulty is that the catalyst will deactivate quickly due to the catalyst was poisoned by S,Cl and other impurities remaining in the raw material.The catalyst will deactivate as well because of the catalyst pores will be blocked easily by raw petroleum resin with large molecular weight.Meanwhile,the softing point and yield of hydrogenated product will get decreased significantly,because of the cracking of petroleum resins.Traditionally,supported Pd,Pt catalysts exhibited excellent activity,but these catalysts deactivate quickly due to the poisoning of noble metal by S,Cl and other impurities remaining in the raw materials.Supported Ni-W-S and Ni-Mo-S catalysts have high abilities of anti-poisoning,however,it can easily give rise to carbon deposition and obtain products with low softening point,because of the strong acidity of these catalysts.Therefore,it is still urgent to develop the catalyst with high activity,high sulfur tolerance and weak acidity for petroleum resin hydrogenation.In this paper,Ni₂P catalysts were applied to the hydrogenation of petroleum resin,which have high activity,good stability,and the softening point of the product has been greatly improved.Traditionally,the Ni₂P catalyst was prepared by temperature-programmed reduction(TPR)method.However,TPR method requires high temperature(650?)to break P-O bond,which leads to high energy consumption,and cause the agglomeration of catalyst particles.For these reasons,we prepared highly dispersive Ni₂P catalysts at low temperature,and we systematically investigated the effects of precursor mixed mode,the precursor P/Ni ratio,phosphating temperature,supports and other factors.On the other hand,in order to improve the mass transfer effect within the pores of the catalyst,the supercritical fluid is introduced into the hydrogenation petroleum resin system,and the impact of the supercritical solvent on the reaction properties was also explored.The main research contents of this paper and the innovations are mainly manifested in the following aspects:1).In LT-MG method,the precursors are NaH₂PO₂and Ni Cl₂?6H₂O,the initial P/Ni=5,phosphating temperature is 400?,SiO₂ as supporter,highly dispersive Ni₂P particles was prepared for the hydrogenation of petroleum resin(Average bromine number in 10 h=86.2 mg Br/100g).2).Pure crystalline phase of Ni₂P was prepared in the initial P/Ni=5,and the phosphating temperature from 250?to 400?.The crystalline phase of Ni₄P₅ and Ni₁₂P₅was get when the initial P/Ni and phosphating temperature were improved.The activity and stability of Ni₂P was much higher than that of Ni₄P₅ and Ni₁₂P₅.It is found that the catalyst was not completely phosphide,and we analyzed the possible reasons.3).The catalytic hydrogenation performance of NiWS/SiO₂ and Ni₂P/SiO₂ was compared.As a result,the average bromine number of the products over Ni₂P/SiO₂was much lower than that of NiWS/SiO₂,showing the higher activity of Ni₂P/SiO₂catalysts.The yield and softening point of hydrogenated products over Ni₂P/SiO₂catalysts were much higher than that over NiWS/SiO₂.And the stability of Ni₂P/SiO₂is better than NiWS/SiO₂.The excellent performance is due to the coordinatively unsaturated surface atoms and high site densities,which make the properties of Ni₂P is similar to noble metal,and the weak acidity of Ni₂P catalysts.4).The reaction conditions were optimized in this paper.Specifically,T=260?,P=6 MPa,LHSV=1 h^-1?In these optimized conditions,the bromine number of the products is lower than 500 mg Br/100g in 120 h.5).The effect of supercritical solvent on the hydrogenation of petroleum resin was discussed.The catalytic activity was significantly improved after the reaction temperature exceeded the critical temperature.Under the investigated solvent,the catalyst with high catalytic activity when we use cyclopentane as solvent,which has lower critical temperature(238.6?)and high solubility of raw materials.