Study On The Residue Demetallation By Reaction-Adsorption

The study focused on the residue hydrodemetallation (HDM) reaction by reaction-adsorption and researched preliminarily reaction behavior of LiaoHe Atmospheric Residue (LHAR) and TaHe Vaccum Residue (THVR). The as-prepared catalyst, HDM mechanism, as well as the distribution and existing form of nickel (Ni) and vanadium (V) were investigated by X-ray diffraction spectroscopy (XRD), scanning electron microscope (SEM), transmission electron microscope (TEM), X-ray energy spectrum(EDX), pyridine adsorption fourier-transform infrared (Py-IR), wavelength dispersive X-Ray fluorescence analysis (XRF) and ultraviolet visible absorption spectroscopy (Uv-vis), respectively.Kaolinite has been a research focus due to its lower price. From Py-IR, the strongest acid is L acid, followed by the mixture of L and B acids, and the lowest acid is B acid when kaolinite was modified by acid and alkali. Adsorption and desorption isotherm of modified kaolinite showed theⅣtype, and the hysteresis loop indicated the B type. The research demonstrated that acid modification was benefitial for aluminum leaching at kaolinite calcination temperature of 600℃and alkali modification was benefitial for silicon extraction at kaolinite calcination temperature of 900℃. The pore diameter became smaller and the surface area became larger as acid and alkali modification time was prolonged.The adsorption process of modified kaolinite adsorbing VOOEP and NiOEP followed the law of Langmuir adsorption isotherm, which indicated that monolayer VOOEP or NiOEP was adsorbed on modified kaolinite; the adsorption quantity increased with enlarging acid strength. The quantity of VOOEP was bigger than the amount of NiOEP using the same adsorbents. The adsorption of metallporphyrin was exothermic in nature and chemical bonds existed between metallorphyrin and modified kaolinite. The adsorption kinetics followed the law of pseudo-first order kinetic mode when modification kaolinite adsorbed metallporphyrin.It was found that intermediate metal porphyrin phenol (MH2) existed during HDM reaction, which showed the reaction sequence, firstly being the hydrogenation of metalporphyrins to metal hydroporphyrins, secondly being the hydrogenolysis of metalhydroporphrins and then resulted in demetallation. Nitrogen and sulfur compounds had great effect on HDM reaction. Nitrogen compounds could inhibit HDM reaction, while sulfur compounds could accelerate HDM reaction, but nitrogen and sulfur compounds coud not change the HDM reaction sequential mechanism. Only when the concentration of sulfur compounds thiophene reached 3100?g/g, would they obviously promoted HDM reaction. The nitrogen compound quinoline had a sensitive effect on HDM reaction. Even small amount could generate large inhabit effect. When the amount of quinoline was 490?g/g, the inhabit effect reached the maximum.The hydrodemetallation(HDM) reaction of metalporphyrin followed a consecutive reaction. The reactions of metal porphyrin forming porphyrin phenol and porphyrin phenol demetallation were first-order reaction, while NiOEP generating NiPH2 and VOOEP generating VOPH2 were the controlling steps when presulfurazation catalyst was used. The reactions of metal porphyrin forming porphyrin phenol and porphyrin phenol demetallation showed as second-order reaction when non-presulfurazation catalyst was used. The experiment found that the activation-energy could be decreased and reaction rate could be increased when presulfurazation catalyst was used.HDM reaction behavior and the metals distribution and existing form of LHAR and THVR were researched by reaction-adsorption. Nickel in LHAR existed mainly in resin and almost no nickel was found in saturate. Nickel and vanadium distributed mainly in heptane asphaltene. Nickel porphyrin in LHAR, Nickel porphyrin and vanadium phorphyrin in THVR mainly were ETIO types, and Nickel porphyrin in LHAR probably existed in DPEP type, and there was probably no RHODO type. As the reaction temperature increased, nickel content decreased in acetone solution and acetone insolution of HDM reaction products of LHAR, but nickel content increased in heptane extract. The metallic compounds of HDM reaction product of THVR were mainly in heptane and benzene extract, which indicated the metallic compounds in heavy components were difficult to remove.