Combined Promoting Effects of Specific Organic Functional Groups and Alumina Surface Characteristics for the Design of a Highly Efficient NiMo/Al_(2)O_(3) Hydrodesulfurization Catalyst

To prepare a highly efficient NiMo/Al_(2)O_(3) hydrodesulfurization catalyst,the combined effects of specific organic functional groups and alumina surface characteristics were investigated.First,the correlation between the surface characteristics of four different alumina and the existing Mo species states was established.It was found that the Mo equilibrium adsorption capacity can be used as a specific descriptor to quantitatively evaluate the changes in surface characteristics of different alumina.A lower Mo equilibrium adsorption capacity for alumina means weaker metal-support interaction and the loaded Mo species are easier to transform into MoS2.However,the Mo-O-Al bonds still exist at the metal-support interface.The introduction of cationic surfactant hecadecyl trimethyl ammonium bromide(CTAB)can further improve Mo species dispersion through electrostatic attraction with Mo anions and interaction of its alkyl chain with the alumina surface;meanwhile,the introduction of ethylenediamine tetraacetic acid(EDTA)can complex with Ni ions to enhance the Ni-promoting effect on Mo.Therefore,the NiMo catalyst designed using alumina with lower Mo equilibrium adsorption capacity and the simultaneous addition of EDTA and CTAB exhibits the highest hydrodesulfurization activity for 4,6-dimethyl dibenzothiophene because of its proper metal-support interaction and more well-dispersed Ni-Mo-S active phases.

Al-modified yolk-shell silica particle-supported NiMo catalysts for ultradeep hydrodesulfurization of dibenzothiophene and 4,6-dimethyldibenzothiophene:Efficient accessibility of active sites and suitable acidity

Yolk-shell SiO2 particles(YP)with center-radial meso-channels were fabricated through a simple and effective method.Al-containing YP-supported NiMo catalysts with different Al amounts(NiMo/AYP-x,x=Si/Al molar proportion)were prepared and dibenzothiophene(DBT)and 4,6-dimethyl-dibenzothiophene(4,6-DMDBT)were employed as the probes to evaluate the hydrodesulfurization(HDS)catalytic performance.The as-prepared AYP-x carriers and corresponding catalysts were characterized by some advanced characterizations to obtain deeper correlations between physicochemical properties and the HDS performance.The average pore sizes of series AYP-x supports are above 6.0 nm,which favors the mass transfer of organic sulfides.The cavity between the yolk and the shell is beneficial for the enrichment of S-containing compounds and the accessibility between reactants and active metals.Aluminum embedded into the silica framework could facilitate the formation of Lewis(L)and Brønsted(B)acid sites and adjust the metal-support interaction(MSI).Among all the as-synthesized catalysts,NiMo/AYP-20 catalyst shows the highest HDS activities.The improved HDS activity of NiMo/AYP-20 catalyst is attributed to the perfect combination of excellent structural properties of the yolk-shell mesoporous silica,enhanced acidity,moderate MSI,and good accessibility/dispersion of active components.

Active phase morphology engineering of NiMo/Al2O3 through La introduction for boosting hydrodesulfurization of 4,6-DMDBT

Herein,we designed and constructed a mesoporous LaAlOx via a solvent evaporation induced self-assembly protocol.The structure and physicochemical property of the corresponding NiMo supported catalyst was analyzed by a set of characterizations,and its catalytic activity was investigated for hydrodesulfurization(HDS)of 4,6-dimethyldibenzothiophene.It has confirmed that the incorporation of La profoundly facilitate the generation of“Type II”NiMoS phase by weakening the interaction of Mo–O–Al leakage and promoting the sulfidation of both Ni and Mo oxides as well as changing the morphology of Ni promoted MoS2 slabs,thereafter boosting the HDS performance substantially.The finding here may contribute to the fundamental understanding of structure-activity in ultra-deep desulfurization and inspire the advancement of highly-efficient HDS catalyst in future.

Tuning active sites in MoS_(2)-based catalysts via H_(2)O_(2)etching to enhance hydrodesulfurization performance

A H_(2)O_(2)etching strategy was adopted to introduce coordinatively unsaturated sites(CUS)on MoS_(2)-based catalysts for dibenzothiophene(DBT)hydrodesulfurization(HDS).The CUS concentrations on MoS_(2) slabs were finely regulated by changing the concentrations of H_(2)O_(2)solution.With the increasing H_(2)O_(2)concentrations(0.1–0.3 mol/L),The CUS concentrations on MoS_(2) slabs increased gradually.However,the high-concentration H_(2)O_(2)etching(0.5 mol/L)increased the MoOxSy and MoO_(3) contents on MoS_(2) slabs compared to etching with the H_(2)O_(2)concentration of 0.3 mol/L,which led to the less CUS concentration in the sulfided Mo–H-0.5 catalyst than in the sulfided Mo–H-0.3 catalyst.A microstructure-activity correlation indicated that the CUS introduced by H_(2)O_(2)etching on MoS_(2) slabs significantly enhanced DBT HDS.Different Co loadings were further introduced into Mo–H-0.3,which had the most CUS concentration,and the corresponding 0.2-CoMo catalyst with the highest CoMoS content(3.853 wt%)exhibited the highest reaction rate constant of 6.95×10^(−6)mol g^(−1)s^(−1)among these CoMo catalysts.

Optimization of dendritic TS-1/Silica micro–mesoporous composites for efficient hydrodesulfurization of dibenzothiophene and 4,6-dimethyldibenzothiophene

A novel composite material(TD)composed of TS-1 microcrystalline and dendritic mesoporous silica nanospheres(DMSNs)was successfully prepared.The TD composite material had open pore structure and large specific surface area,which was conducive to the mass transfer of reactants and products.The Ti element in TS-1 could be used as an electron assistant,and the spillover d-electrons were conducive to the improvement of the sulfidation and dispersion of MoS_(2),thereby forming more type II MoS_(2) active phases.The incorporation of Ti could bring more Brønsted(B)and Lewis(L)acid,which was conducive to the hydrogenation pathway(HYD)selectivity(41.2%)of dibenzothiophene(DBT)hydrodesulfurization(HDS)and isomerization(ISO)route selectivity(21.9%)of 4,6-dimethyldibenzothiophene(4,6-DMDBT)HDS,thus improve the HDS activity of DBT and 4,6-DMDBT.NiMo/TD-70(Aging temperature=70℃)had the best HDS activities of DBT(99.0%)and 4,6-DMDBT(93.7%)due to its large open pore structure,good acidity,suitable metal-support interaction(MSI)and perfect dispersion of the metallic active sites.

Highly Active Sulfided NiPMo Hydrodesulfurization Catalyst Prepared from Keggin-type Phosphomolybdic Acid

A highly active sulfided NiPMo/MCM-41(NiPMo-S/M41)hydrodesulfurization(HDS)catalyst was successfully synthesized using Keggin-type phosphomolybdic acid as the phosphorus and molybdenum source and thioacetamide as the sulfur source.The supported catalysts NiPMo/M41,Ni_(2)P-Mo/M41,and Ni_(2)P/M41 were also prepared to investigate the effects of Mo,S,and the Keggin structure on the HDS performance.The HDS activities of NiPMo/M41 and NiPMo-S/M41 toward dibenzothiophene were much higher than that of Ni_(2)P-Mo/M41,demonstrating that the active phases in the Keggin-structured catalysts were significantly superior to the Mo-modified Ni_(2)P phase.The HDS activities of the catalysts followed the order NiPMo-S/M41(96.7%)>NiPMo/M41(89.9%)>Ni_(2)P-Mo/M41(53.5%)>Ni_(2)P/M41(48.9%).For Ni_(2)P/M41,Ni_(2)P-Mo/M41,and NiPMo/M41,cyclohexylbenzene(CHB)was formed in low concentrations(<21.0%),indicating that direct desulfurization was the favored reaction route and that this did not change for Keggin-structured NiPMo/M41.By contrast,the CHB selectivity of NiPMo-S/M41 increased to 44.6%,much higher than that of NiPMo/M41(17.6%),demonstrating that sulfidation enhanced the hydrogenation ability,which was ascribed to a metal-acid synergistic effect.

Preparation of highly dispersed desulfurization catalysts and their catalytic performance in hydrodesulfurization of dibenzothiophene

Micro-mesoporous ZK-1 molecular sieves with different Si/Al ratios were used as supports for binary Co-Mo hydrodesulfurization（HDS） catalysts.The CoMo/ZK-1 catalysts were prepared using an over-loading impregnation method,and characterized using N2 physisorption,X-ray diffraction,temperature-programmed NH3 desorption,temperature-programmed reduction（TPR）,ultraviolet-visible diffuse reflectance spectroscopy,and high-resolution transmission electron microscopy（HRTEM）.The results show that the CoMo/ZK-1 catalysts have high surface areas（～700 m^2/g）,large pore volumes,and hierarchical porous structures,which promote the dispersion of Co and Mo oxide phases on the ZK-1 supports.The TPR results show that the interactions between the Co and Mo oxide phases and the ZK-1 support are weaker than those in the CoMo/γ-Al2O3 catalyst.The HRTEM results show that the CoMo/ZK-1 catalysts have better MoS2 dispersion and more active edge sites.The catalysts were tested in HDS of dibenzothiophene.Under mild reaction conditions,the activity of Co and Mo sulfides supported on ZK-1 was higher than those of Co and Mo sulfides supported on ZSM-5,A1KIT-1,and γ-Al2O3.

Preparation, Characterization, Hydrodesulfurization and Hydrodenitrogenation Activities of Alumina-supported Tungsten Phosphide Catalysts

Two series of WP/Al2O3 catalyst precursors with WP mass loading in the range 18.5%—37.1% were prepared using the impregnation method and mixing method, respectively, and the catalysts were then obtained by temperature-programmed reduction of supported tungsten phosphate (precursor of WP/Al2O3 catatlysts) in H2 at 650℃ for 4h. The catalysts were characterized by XRD, BET, TG/DTA , XPS and 31P MAS-NMR. The activities of these catalysts were tested in the hydrodenitrogenation (HDN) of pyridine and hydrodesulfurization (HDS) of thiophene at 340℃ and 3.0MPa. The results showed that owing to the stronger interaction of the support with the active species, the precursor of WP/Al2O3 catalyst was more difficultly phosphided and a greater amount of W spe- cies was in a high valence state W6+ on the surface of the catalyst prepared by the impregnation method than that by the mixing method. 31P MAS-NMR results indicated that 31P shift from 85% H3PO4 of 2.55×10-4 for WP and 2.57 ×10-4 for WP/γ-Al2O3 catalysts prepared by mixing method. Such WP/Al2O3 catalysts showed higher HDN activi- ties and lower HDS activities than those prepared by the impregnation method under the same loading of WP. WP/γ-Al2O3 catalysts with weak interaction between support and active species were favorable for HDN reaction while the WP/γ-Al2O3 catalysts with strong interaction were favorable for HDS reaction.

Ni-_2P-MoS_2/γ-Al_2O_3 Catalyst for Deep Hydrodesulfurization via the Hydrogenation Reaction Pathway

A series of highly active Ni2P-Mo S2/γ-Al2O3 catalysts were prepared and characterized, the catalytic performance of which was evaluated through hydrodesulfurization of dibenzothiophene. The result indicated that when the amount of Ni2 P was 4%, the catalyst showed a relatively high activity to provide a reliable reference for the hydrodesulfurization pathway in comparison with the conventional Ni Mo and Ni Mo P catalysts. The physicochemical properties of the catalysts were correlated with their catalytic activity and selectivity on hydrodesulfurization. The stacking number of active Mo S2 phases was important for influencing the hydrogenation activity.

NiMo/Al_2O_3 catalyst containing nano-sized zeolite Y for deep hydrodesulfurization and hydrodenitrogenation of diesel

Two mixed-matrix NiMo/Al2O3 catalysts containing nano-and micro-sized zeolite Y have been prepared to explore the size effect of zeolite Y particle on the hydrodesulfurization（HDS）and hydrodenitrogenation（HDN）activities of fluid catalytic cracking（FCC）diesel.They were characterized by SEM,BET,XRD,H2-TPR,NH3-TPD and HRTEM.The results show that the catalyst containing nano-sized zeolite Y possesses larger average pore diameter,higher pore volume,weaker and lesser acid sites,more easily reducible metal phases,shorter MoS2 slabs and more slab layers than the catalyst containing micro-sized zeolite Y.The catalysts were also evaluated with a high-pressure fixed-bed reactor using real FCC diesel as feed.The results display that the catalyst containing nano-sized zeolite Y bears higher HDS and HDN activities and exhibits higher relative rate constant for the removal of total sulfur or nitrogen than the one containing micro-sized zeolite.

Hydrodesulfurization activities of NiMo catalysts supported on mechanochemically prepared Al-Ce mixed oxides

Al2O3-CeO2 supports containing 1-10 wt%Ce were prepared mechanochemically by milling aluminum and/or cerium nitrates with NH4HCO3.Heteropolymolybdate,（NH4）4NiMo6O（24）,was used as the precursor of the Ni and Mo to prepare NiMo6/Al2O3-CeO2 components in catalysts by impregnation method.The physicochemical properties of the catalysts were determined using chemical analysis,X-ray diffraction,temperature-programmed H2 reduction,temperature-programmed NH3 desorption,X-ray photoelectron spectroscopy（XPS）,and the Brunauer-Emmett-Teller method.The catalyst acidity decreased with increasing Ce concentration in the support.XPS showed that the NiS/MoS ratio decreased two-fold for the Ce-modified alumina support.NiMo6/Al2O3,which had the highest acidity,showed the highest activity in hydrodesulfurization of 1-benzothiophene（normalized per weight of catalyst）.The concentration of surface MoOxSy species（which is equal to the concentration of Mo^（5＋）） gradually decreased to zero for catalysts with Ce concentrations 10 wt%.However,the activities of all the catalysts prepared mechanochemically from Al2O3 and Al2O3-CeO2supports significantly exceeded that of a reference NiMo6/Al2O3 catalyst prepared by impregnation method using the same precursor and with the same composition.

Support Effects on Thiophene Hydrodesulfurization over Co-Mo-Ni/Al_2O_3 and Co-Mo-Ni/TiO_2-Al_2O_3 Catalysts

A carbon-based sulfonated catalyst was prepared by direct sulfonation and carbonization （in moderate conditions：200 ＆#176;C, 12 h） of red liquor solids, a by-product of paper-making process. The prepared sulfonated cata-lyst （SC） had aromatic structure, composed of carbon enriched inner core, and oxygen-containing （SO3H, COOH, OH） groups enriched surface. The SO3H, COOH, OH groups amounted to 0.74 mmol·g^-1, 0.78 mmol·g^-1, 2.18 mmol·g^-1, respectively. The fresh SC showed much higher catalytic activity than that of the traditional solid acid catalysts （strong-acid 732 cation exchange resin, hydrogen type zeolite socony mobile-five （HZSM-5）, sulfated zir-conia） in esterification of oleic acid. SC was deactivated during the reactions, through the mechanisms of leaching of sulfonated species and formation of sulfonate esters. Two regeneration methods were developed, and the catalytic activity can be mostly regenerated by regeneration Method 1 and be fully regenerated by regeneration Method 2, respectively.

Development and CommercialApplication of RSDS-II Technology for Selective Hydrodesulfurization of FCC Naphtha

The FCC naphtha selective hydrodesulfurization technology(RSDS-II)has been tested with different feedstocks in pilot scale.The results show that RSDS-II technology is viable in terms of its adaptability to different feedstocks.To produce gasoline with a sulfur content of less than 50μg/g by the RSDS-II technology,the gasoline RON loss is less than 1.8,0.9and 0.2 units,respectively,upon processing the conventional high-sulfur and high-olefin FCC naphtha,the high-sulfur MIP naphtha,and the medium-sulfur or low-sulfur MIP naphtha.Upon using the naphtha produced from pre-hydrotreated FCC feedstock as the RSDS-II feedstock to manufacture gasoline with a sulfur content of lower than 10μg/g,the RON loss does not exceed 1.0 unit.The RSDS-II technology has been commercialized successfully at many refineries.The result of operating commercial RSDS-II unit at the Shanghai Petrochemical Company has revealed that upon processing a feedstock containing 38.7 v% —43.3 v% of olefins and 250—470 mg/g of sulfur,the sulfur content in the treated gasoline ranges from 33μg/g to 46μg/g and the RON loss is equal to only 0.3—0.6 units.Till now this RSDS-II unit has been operating smoothly over 30 months.Thanks to its high HDS activity and good selectivity,the RSDS-II technology can meet the refinery’s needs for adequate upgrading of gasoline.

Development of New Generation Catalysts for Selective Hydrodesulfurization of FCC Naphtha

The influence of active metal components of catalyst, additives and catalyst preparation method on the reactivity of catalyst for selective hydrodesulfurization (HDS) of FCC naphtha was investigated, and the RSDS-21 catalyst with high HDS performance and the RSDS-22 catalyst with high selectivity were developed by RIPP. The composite loading of a new series of catalysts for selective HDS of FCC gasoline has demonstrated excellent desulfurization activity and selectivity and can under conventional hydrotreating conditions manufacture clean gasoline product meeting the national IV emission standard and the Euro V emission standard with less loss in antiknock index. The finalized new series of FCC catalysts upon being adopted for selective HDS of FCC naphtha have good adaptability to different feedstocks along with good stability.

Ni_2P/ZrO_2-SBA-15 Dibenzothiophene Hydrodesulfurization Catalysts: Preparation,Characterization and Evaluation

Ni_2P/ZrO_2-SBA-15 catalysts with different zirconium n-propoxide/SBA-15 mass ratios were synthesized to evaluate their dibenzothiophene hydrodesulfurization catalytic activity. Effect of ZrO_2 introduction was investigated. Supports and catalysts were characterized by BET,XRD,^(29)SiNMR,XPS and FTIR. The results indicated that zirconium was incorporated into SBA-15 in the forms of [(–O–)_2 Si(–O–Zr)_2 ] and/or [(–O–)_3 Si–O–Zr],and that the SBA-15 framework structure was maintained after incorporation of ZrO_2. With zirconium content increasing,ZrO_2 was transformed from amorphous phase to tetragonal phase. Zirconium incorporation into SBA-15 supports could facilitate to form more dispersed Ni_2P active phase. There might be some interaction occurring between the P and Zr species. In addition to Ni_2P,another kind of active phase,ZrP,was formed,which might exhibit a better HDS activity than Ni_2P. It was observed that at a temperature of 280 °C,pressure of 3.0 MPa,WHSV of 6.5 h^(-1) and H_2 to oil ratio of 450,the Ni_2P/Zr-SBA(1.5) catalyst,where 1.5 represents zirconium n-propoxide/SBA-15 mass ratio,showed the highest DBT conversion,which was 86.6%,almost 35% higher than that of the Ni_2P/Zr-SBA(0) catalyst.

The tuning of pore structures and acidity for Zn/Al layered double hydroxides:The application on selective hydrodesulfurization for FCC gasoline

Co–Mo catalysts applied on the hydrodesulfurization（HDS） for FCC gasoline were prepared with Zn–Al layered double hydroxides（LDHs） to improve their performances,and the effects of pore structures and acidity on HDS performances were studied in detail. A series of Zn–Al/LDHs samples with different pore structures and acidities are synthesized on the bases of co-precipitation of OH-,CO2-,Al3＋,and Zn2＋. The neutralization p H is a main factor to affect the pore structures and acidity of Zn–Al/LDHs,and a series of Zn–Al/LDHs with different pore structures and acidities are obtained. Based on the representative samples with different specific surface areas（SBET） and acidities,three Co Mo/LDHs catalysts were prepared,and their HDS performances were compared with traditional Co Mo/Al2O3 catalysts. The results indicated that catalysts prepared with high SBETpossessed high HDS activity,and Br？nsted acid sites could reduce the thiol content in the product to some extent. All the three catalysts prepared with LDHs displayed little lower HDS activity but higher selectivity than Co Mo/Al2O3,and could restrain the reactions of re-combination between olefin and H2 S which could be due to the existence of Br？nsted acid sites.

The effect of chelating agent on hydrodesulfurization reaction of ordered mesoporous alumina supported Ni Mo catalysts

In this paper,ordered mesoporous alumina(OMA)support with the high surface area(328 m^(2)g^(-1))and the large pore volume 0.74(cm^(3)·g^(-1))was synthesized by homogeneous precipitation method.And the influence of EDTA on the physical and chemical properties of the modified catalysts was also studied.The characteristic results showed that the addition of EDTA could adjust the metal-support interaction and improved the acidity of the corresponding catalyst.Combined with the catalytic performance results,the EDTA-modified Ni Mo E(1.0)/OMA catalyst displays the highest DBT hydrodesulfurization conversion(97.7%).

In situ FT-IR spectroscopy investigations of carbon nanotubes supported Co-Mo catalysts for selective hydrodesulfurization of FCC gasoline

To better understand the nature of carbon nanotubes supported Co-Mo catalysts （Co-Mo/CNTs） for selective hydrodesulfurization （HDS） of fluid catalytic cracking （FCC） gasoline, studies are carried out using in situ Fourier transform infrared spectroscopy （FT-IR）. The catalytic performances of Co-Mo/CNTs catalysts were evaluated with a mixture of cyclohexane, diisobutylene, cyclohexene, 1-octene （60 ： 30 ： 5 ： 5, volume ratio） and thiophene （0.5%, ratio of total weight） as model compounds to simulate FCC gasoline. The HDS experimental results suggested that the HDS activity and selectivity of Co-Mo/CNTs catalysts were affected by Co/Mo ratio; the optimal Co/Mo atomic ratio is about 0.4, and the optimum reaction temperature is 260 ℃. The in situ FT-IR studies revealed that 1-octene can be completely saturated at 200 ℃. In the FT-IR spectra of diisobutylene, the characteristic absorption peak around 3081 cm^-1 for the stretching vibration peak of =C-H bond was still clear at 320 ℃ indicating that diisobutylene is difficult to be hydrogenated. As for the thiophene, no characteristic absorption peak could be found around 3092 cm^-1 and 835 cm^-1 when the reaction temperature was raised to 280 ℃, indicating that thiophene had been completely hydrodesulfurized. On the basis of FT-IR results, it can be deduced that thiophene HDS reaction occurred mainly through direct hydrogenolysis route, whereas thiophene HDS and diisobutylene hydrogenation reaction over Co-Mo/CNTs catalysts might occur on two different kinds of active sites.

Kinetic Study on Liquid-Phase Hydrodesulfurization of FCC Diesel in Tubular Reactors

According to the characteristics of FCC diesel, a technology of liquid-phase hydrodesulfurization of the diesel in tubular reactors was proposed and lab-scale experiments were carried out. A kinetic model for the hydrodesulfurization process was developed and verified. The model was utilized to predict the sulfur content of products under different operating conditions. The effects of temperature, space velocity, pressure, and hydrogen concentration on the dcsulfurization rate were investigated.

Effects of pore size,mesostructure and aluminum modification on FDU-12 supported NiMo catalysts for hydrodesulfurization

A series of NiMo/FDU-12 catalysts with tunable pore diameters and mesostructures have been controllably synthesized by adjusting the synthetic hydrothermal temperature and applied for the hydrodesulfurization of dibenzothiophene and its derivative.The state-of-the-art electron tomography revealed that the pore sizes of FDU-12 supports were enlarged with the increase in the hydrothermal temperature and the mesostructures were transformed from ordered cage-type pores to locally disordered channels.Meanwhile,the MoS2 morphology altered from small straight bar to semibending arc to spherical shape and finally to larger straight bar with the change of support structures.Among them,FDU-12 hydrothermally treated at 150℃possessed appropriate pore diameter and connected pore structure and was favorable for the formation of highly active MoS2 with curved morphology;thus,its corresponding catalyst exhibited the best HDS activity.Furthermore,it was indicated that the isomerization pathway could be significantly improved for HDS of 4,6-dimethyldibenzothiophene after the addition of aluminum,which was expected to be applied to the removal of the macromolecular sulfur compounds.Our study sheds lights on the relationship between support effect,active sites morphology and HDS performance,and also provides a guidance for the development of highly active HDS catalysts.