Upgrading Of Shale Oil By Hydrotreatment

Shale oil contains higher heteroatoms than crude oil,and especially its high N content are detrimental to the further utilization of shale oil in the refinery.Shale oil can be upgraded by hydrotreatment,and the quality of hydrotreated shale oil is even better than that of crude oil.For example,the hydrotreated shale oil under certain conditions can contain lower N content than Shengli crude oil does.Consequently,the paper carried out studies on the hydrotreatment of shale oil for oil upgrading.The acquired main conclusions in this work are summarized below.1.Analysis of compound species for virgin and hydrotreated shale oil.Fushun furnace-Huadian shale Oil(FHO)and their hydrotreated products(HFHO)shown by HFHO-NiMo,HFHO-NiW and HFHO-CoMo were characterized using positive-ion mode APPI FT-ICR MS.More than 20 000 peaks were detected in the obtained spectra.In FHO,N1 and N1O1 species are the dominant N compounds and the other N species include,for example,N1O2,N2,N1S1,N1O1S1 and N1O3.Of S compounds,the S1 species are the major type because there are very few S2 species.The primary aromatic hydrocarbon(AHC)species are mono-and double-ring aromatics.After hydrotreatment,both S and N compounds in FHO are effectively removed.The NiMo catalyst exhibits the best catalytic performance for HDS and HDN of shale oil.In hydrotreated shale oils,N1 species reduced but were still the dominant N compound,and all the other N species were very few.The primary N1 species are indole,carbazole,acridine and their derivatives.The content of S1 species is very low and that of S2 species is close to zero.AHC species of mono-and double-ring aromatics still have high relative abundance,especially the mono-ring aromatics.Because of the high relative abundances of N1 and N1O1 species,the transformation between both species enables a better understanding of HDN for shale oil.The relative abundances of AHC species are enhanced as a result of the transformation of N1,N1O1,and S1 species into AHC species via hydro treatment.2.Process conditions and kinetic models for shale oil hydro treatment.After hydrotreatment,the yield of hydrotreated shale oil is higher than 99 wt.%,and the C1-C4 composition in exhaust gas is little influenced by the H2/Oil volume ratio,liquid hourly space velocity(LHSV),temperature and pressure.The conditions of high H2/Oil volume ratio,high temperature and pressure,and low LHSV are beneficial to HDS and HDN,especially to HDN.The preferred H3/Oil volume ratio is 600 Nm3/m3 for the FHO hydrotreatment.And HFHO contains 0.021 wt.%S and 0.39 t.%N under conditions of 350 ?,8.0 MPa,600 Nm3/m3 of H2/Oil volume ratio and an LHSV of 1.0 h-1.These data values are lower than those of Shengli crude oil.When hydrotreating FHO,IHO(Internal furnace-Huadian shale Oil)and FLO(Fushun furnace-Longkou shale Oil),the compositions of their exhaust gases little differred from each other,and the yields of hydrotreated shale oil were all higher than 99 wt.%.The realized HDS conversions differred little and were bigger than the HDN conversions.The FLO may have high content of active N compounds which is prone to HDN.It had thus the largest N content and meanwhile the highest HDN conversion.Both FHO and IHO may have similar contents of S and N species so that they have almost the same HDS and HDN conversions at every tested temperature.Based on the data from hydrotreatment tests,the HDS and HDN macro-kinetic models were developed.The HDS reaction index to H2 partial pressure is 0.24,lower than 1.01 for HDN.Thus,the HDN reaction was more influenced by H2 partial pressure than the HDS reactions did.Meanwhile,the HDN is more difficult and more seriously influenced by temperature in comparison with HDS.Thus,the HDN reaction had the higher activation energy of 117.55 kJ/mol than 43.84 kJ/mol for the HDS reaction.3.Stability of industrial catalyst in shale oil hydro treatment.During 30-day runtime,the C1-C4 compositions of exhaust gas little varied,and the yields of HFHO were above 99 wt.%.The HDS activity was stable because the HDS conversion was higher than 95%and declined very little.The initial HDN conversion was above 90%,and it continuously decreased in the first 5 days of running.Then,the HDN activity became stable and its conversion was about 85%in 6 to 30 days of running.The variations of HDS and HDN performance with time may be caused by carbon deposition on catalyst.In the initial stage of reactions,the N-containing heterocyclic compounds largely adsorbed on the surface of catalyst having high initial activity so that the carbon deposition rose quickly.In turn,the carbon deposition varied very little to show the stable catalytic activity.Because N-containing heterocyclic compounds are hardly directly removed by hydrogenolysis but they adsorb firstly on the catalyst surface such that the carbon deposition inhibits more severely the HDN than HDS reactions.The performance of hydrotreatment also varied with the position of catalyst bed.The carbon deposition of catalyst bed near the reactor outlet is lower because the shale oil encountered there contains low content of S and N.4.Reactor model and reactor design of 100 000 t/a shale oil hydrotreatment.A reactor model is established on the basis of HDS and HDN macro-kinetic models for shale oil hydrotreatmet.The reactor temperature rise is about 90 ? without a quench zone.When the inside of reactor is quenched using cold H2,the HDS and HDN conversions are higher,and the S and N contents in hydroytreated oil are lower in comparison with the case using cold shale oil as the cooling medium.When the reactor is quenched using shale oil,the device capacity and S&N removal efficiencies all increased.The enhanced utilization of catalyst bed will benefit the long-term running of the reactor.The reactor model provides parameters for reactor design,and we obtained the basic structure parameters of a hydrotreatment reactor at 100 000 t/a including the catalyst loading,reactor diameter,quench conditions,reactor pressure drop,etc.5.Process simulation of 100 000 t/a shale oil hydrotreatment.Water in Low Pressure Separator has certain absorption of N compounds,and water injection plays an important role in absorption of H2S and NH3 from gas flow.Both HDS and HDN can be enhanced by increasing temperature,meanwhile the upper and lower limits of injected water flow rate also increase.The increased system pressure can also enhance the HDS and HDN performances,and improve the absorption of H2S and NH3.These decrease the water flow rate limits,and especially the upper water flow limit showed obvious decrease.The H2S absorption in Amine Washing Tower linearly varies with MDEA content.The operational parameters obtained in process simulation is essential for engineering design.6.Carrier,active component and promoter of catalyst.The carrier sample Al-P0.3-600 has better textural properties than the other two samples,Al-LNHT and Al-RIPP.Meanwhile,the NiMo/Al-PO.3-600 catalyst has the largest specific surface area and porous volume in comparison to the other two catalysts of NiMo/Al-LNHT and NiMo/Al-RIPP.NiMo/Al-LNHT has the slightly lower activity than NiMo/Al-PO.3-600 does,and the activity of NiMo/Al-RIPP is the lowest.For hydrotreatment of shale oil,the preferred pore size of catalyst is in the range of 6-10 nm.The NiMo is the preferred active component of catalyst because NiMo/Al2O3 showed the higher HDS and HDN activities than the other two catalysts NiW/Al2O3 and CoMO/Al2O3 did.In comparison with NiMo/Al2O3 and NiMoS/Al2O3-SiO2-p,the NiMo/Al2O3-SiO2-d modified with dispersed nano-Si02 has the higher S content,higher Mo sulfidation degree,lower carbon deposition,lower low-and high-reduction temperatures,more weak-and mid-acid sites,and more dispersed and smaller MoO3 particles.The catalyst NiMo/Al2O3-SiO2-d has the higher HDN and lower HDS activities than the other two catalysts do,as shown by evaluation tests in an autoclave with its outlet valve closed.The reason may be that the large amount of NH3 formed in HDN inhibited HDS.The inhibition becomes stronger with enhanced HDN activity or increased temperature.