Реферат: The triglyceride feedstocks (non-edible and waste cooking oils, animal fats) are the attractive renewables for the production of motor fuel component (C12-C18 alkanes), that are compatible with the petroleum-derived gas oil and improves its properties. Hydrodeoxygenation (HDO) of triglycerides (TG) can be performed in the stand-alone units or via the co-processing with the petroleum oil in the existing refinery, in both cases sulfide Co(Ni)Mo/Al2O3 catalysts are employed. The drawback of the sulfide catalyst is its deactivation due to sulfur loss; the expensive sulfiding agent should be used to preserve the sulfide state of catalysts. One of the approaches to solve this problem is the development of sulfur-free catalysts containing base metals, their carbides, nitrides or phosphides. As well, co-processing of TG with petroleum feeds is the cost-effective solution improving the fuel properties and avoiding the addition of sulfiding agent. HDO of TG can proceed via H2O removal (direct HDO pathway – DHDO) or through the CO/CO2 elimination (HDeCOx route), which can lead to the additional hydrogen consumption in the methanation reaction and demands the purification of recycle hydrogen. In the current work we illustrate the enhancing of catalytic activity or selectivity though the cooperation of catalytic systems with different functionality in the HDO of aliphatic compounds. Firstly the peculiarities of stack-bed technology are discussed which allows to avoid COx formation during the ULSD production from the mixture of straight run gas oil (SRGO) and rapeseed oil (RSO) and improve cold flow properties of the final products. Then the enhancement of catalytic activity of MoP/SiO2 and Ni2P/SiO2 catalysts in methyl palmitate (MP) hydrodeoxygenation is shown, that is result of catalyst dilution with γ-alumina or zeolites. The MoP/SiO2, Ni2P/SiO2 samples and sulfided MoS2 and Co(Ni)-MoS2 catalysts supported on alumina or zeolite-containing granules were prepared by impregnation of the supports with the solution of precursors with the subsequent drying and activation immediately before experiment in the catalytic reactors [1-3]. The catalysts were studied using chemical analysis (ICP-AES), N2 physisorption, H2-TPR, XRD, XPS and TEM. The hydrotreating of SRGO-RSO mixtures was performed using granulated sulfide catalysts in the pilot plant units [3].The HDO of MP was carried out in the trickle-bed down-flow reactor over silica-supported phosphide (Ni2P, MoP) catalyst mixed with SiC, alumina or zeolites; accompanied by GC analysis of liquid and gas phases, oxygen analysis using Vario EL Cube analyzer. To prevent COx formation in the course of SRGO-RSO hydrotreatment we proposed to use selective MoS2/Al2O3 catalyst in the front bed of the reactor and supported sulfide Co(Ni)- MoS2 catalysts in the second layer. The comparison of the behavior of CoMo/Al2O3, NiMo/Al2O3 catalysts and the stacked-bed catalytic systems (MoS2/Al2O3 –Co(Ni)Mo/Al2O3) in the SRGO-RSO hydrotreatment (340°C, 4.0 MPa, H2/feed - 600 Nm3/m3, LHSV- 1.5 h-1; RSO content – 10,15 and 30 wt.%) has shown, that the quality of the products depends more on the amount of RSO than on the nature of the catalysts. In the case of stacked-bed system we did not detect COx among the reaction products that pointed out to the selective transformation of RSO via HDO routes in the front layer, containing MoS2/Al2O3 catalyst. Thus, the cooperation of MoS2/Al2O3 catalyst (providing selective HDO of RSO) and traditional hydrotreating catalysts (providing the deep hydrotreating of SRGO) allows ULSD production from SRGO-RSO mixture without COx formation, that increase the yield of diesel fuel and avoid the problems associated with the purification of recycle hydrogen. The using of Co(Ni)-MoS2 catalysts supported on zeolite-containing granules (30wt% SAPO-11/70wt.% Al2O3) instead of conventional sulfide Co(Ni)Mo/Al2O3 catalysts in stacked bed systems allows decreasing cloud point of the hybrid diesel fuel due to isomerization and cracking of n-C18, produced in HDO of rapeseed oil [4]. The study of silica-supported phosphide-type catalysts mixed with the inert (SiC) or acidic (γ-Al2O3) material in methyl palmitate HDO (250–330°C, 3.0 MPa, H2/feed - 600 Nm3/m3, WHSV 5 h-1) let us see, that MP conversion increases significantly when γ-Al2O3 is used instead of SiC [1,2]. HDO of aliphatic esters into hydrocarbons proceeds through a complicated reaction network, including metal-catalyzed hydrogenolysis of C–O and C–C bonds, hydrogenation reactions and acid-catalyzed hydrolysis and dehydration reactions. Methyl palmitate conversion to the oxygenated intermediates is shown to be the rate-determining step over the MoP/SiO2–SiC or Ni2P/SiO2–SiC systems, and could be increased due to the acceleration of ester hydrolysis over acid sites of alumina. Thus, the synergsm of Ni2P/SiO2 and γ-Al2O3 physical mixture in methyl palmitate HDO could be explained by the cooperation of the metal sites of phosphides and acid sites of γ-Al2O3 in the providing of metal and acid-catalyzed reactions. This observation would play an important role in the development of the effective catalyst for the HDO of fatty acid esters over supported phosphide catalysts.

Библиографическая ссылка: Bukhtiyarova G.A. , Vlasova E.N. , Shamanaev I.V.
The Selected Examples of Catalytic Materials Cooperation in the Hydrodeoxygenation of Aliphatic Oxygenates to the Motor Fuel Components
2021 Sino-Russian High-Level International Symposium on Catalysis 21-22 May 2021