Preparation Of Cu/(ZnO)/FeO_x Catalysts And Their Catalysis In The Viscosity Reduction Of Heavy Crude Oil Cooperating With Oxalic Acid

The world today is undergoing profound changes unseen in a century and the international situation is extremely complex.The rapid population growth and economic development are leading to an increasing demand for energy,among which the consumption of conventional petroleum resources is increasing exponentially.In order to alleviate the tension of energy shortage,the exploitation and utilization of unconventional petroleum resources to the maximum extent has become one of the hot spots in the current development of petroleum industry.It is reported that heavy crude oil,as a special unconventional petroleum resource,accounts for about 50%of the world’s total oil reserves.However,heavy crude oil has brought great difficulties to exploitation due to its characteristics of high viscosity and poor fluidity.With people’s understanding of heavy crude oil,different viscosity reduction technologies for heavy oil have been proposed.the catalytic aquathermolysis has the most potential.aims to make use of the characteristics of metal ions to interact with heavy oil macromolecules to promote ring opening,cracking,hydrocatalysis and other reactions of heavy components,so as to achieve the purpose of structural reorganization and viscosity reduction of heavy oil.In this paper,the catalysis of the two catalysts(i.e.,Cu/FeO_x and Cu/ZnO/Fe O_x,)in the viscosity reduction of heavy crude oil cooperating with oxalic acid was studied.Through oxidative cracking,catalytic hydrogenation and other reactions,the recovery of heavy oil viscosity is inhibited and irreversible viscosity reduction occurs at the same time,and finally achieve the purpose of improving the quality of heavy oil.First,the Cu/Fe O_x catalysts were prepared through hydrothermal method and reduction in H₂/Ar current and were characterized by XRD,SEM,TEM,etc.The effect of the Cu/Fe ratio and the reduction time and temperature in H₂/Ar current on the composition and structure of Cu/Fe O_x catalysts was investigated.Subsequently,the synergistic effect of the Cu/Fe O_xcatalysts and oxalic acid on the catalytic viscosity reduction of extra heavy crude oil was also studied.According to the results of catalytic performance,four components（SARA:Saturates,Aromatics,Resins,and Asphaltenes）and element analysis,the synergy mechanism of the catalysts and oxalic acid when they were used in the catalytic viscosity reduction of heavy crude oil was supposed.Finally,in order to increase the dispersity of Cu species on the catalyst,Cu/Zn O/Fe O_xcatalysts were prepared by similar method,and the mechanism of the catalytic viscosity reduction of heavy crude oil was discussed by analyzing the results of characterization and evaluation of catalytic performance.（1）Preparation of Cu/FeO_x catalysts and their catalysis in the viscosity reduction of heavy crude oil cooperating with oxalic acidIn this chapter,the Cu/Fe complex precursors were first prepared by hydrothermal method with Fe（NO₃）₃·9H₂O as iron source and Cu（NO₃）₂·3H₂O as copper source,respectively,and then the final Cu/Fe O_x catalysts were obtained through reduction treatment in H₂/Ar（H₂≥10%）current.The synergistic effect of the Cu/Fe O_x catalysts and oxalic acid on the catalytic viscosity reduction of extra heavy crude oil was studied.The results of XRD,SEM,TEM,etc.show that the composition of Cu/Fe-20/80 complex precursor was transformed to the mixture of Cu⁰,α-Fe₂O₃ and Fe₃O₄ after being reduced in H₂/Ar（H₂≥10%）current at 230℃for 1 h in a tubular furnace.The morphology is primarily the porous cubic,of which Cu elements gather in the pores.Meanwhile,the catalyst prepared under this condition showed the best activity for the viscosity reduction of heavy crude oil when cooperating with oxalic acid.The viscosity reduction rate is 41.74%.The mechanism of the catalytic viscosity reduction of heavy crude oil was discussed not only through analyzing the results of SARA and C,H,N,S element contents of oil samples before&after catalyst reaction and but also through detecting the products of oxalic acid decomposition with/without the existence of Cu/Fe O_x catalyst by means of GC-TCD.（2）Preparation of Cu/ZnO/FeO_x catalysts and their catalysis in the viscosity reduction of heavy crude oil cooperating with oxalic acidIn this chapter,Zn was doped in the Cu/Fe composite to increase the dispersity of Cu species,thus improving the catalytic viscosity reduction of extra heavy crude oil.Cu/Zn O/Fe O_xcatalysts were prepared through hydrothermal method and reduction in H₂/Ar（H₂≥10%）current and were characterized by XRD,SEM,TEM,etc.with Zn（NO₃）₂·6H₂O,Fe（NO₃）₃·9H₂O,and Cu（NO₃）₂·3H₂O as the zinc source,iron source,and copper source,respectively.The results show that the catalyst Cu/Zn O/Fe O_x,which was obtained through treating Cu/Zn/Fe-20/10/70 in H₂/Ar（H₂≥10%）current at 190℃for 1 h,shows the best the best activity for the viscosity reduction of heavy crude oil when cooperating with oxalic acid.The viscosity reduction rate is 44.09%.XRD result shows that no Cu⁰ phase was detected,indicating that Cu species was well dispersed.TEM and SEM results demonstrate that the catalyst Cu/Zn O/Fe O_x consists of homogeneous hollow nanoparticles and the Cu element is evenly dispersed on the nonoparticles.The mechanism of the catalytic viscosity reduction of heavy crude oil was supposed through analyzing the results of SARA and C,H,N,S element contents of oil samples before&after catalyst reaction.