The surface properties of aluminated meso–macroporous silica and its catalytic performance as hydrodesulfurization catalyst support

Aluminated mesoporous silica was prepared by multiple post-grafting of alumina onto uniform mesoporous SiO_2 ,which was assembled from monodisperse SiO_2 microspheres.Hydrodesulfurization(HDS)catalyst was prepared by loading Ni and Mo active components onto the aluminated uniform mesoporous SiO_2 ,and its HDS catalytic performance was evaluated using hydrodesulfurization of dibenzothiophene as the probe reaction at 300°C and 6.0 MPa in a tubular reactor.The samples were characterized by N_2 physisorption,scanning electronic microscopy,Fourier transform infrared spectrum,X-ray diffraction(XRD),temperature-programmed desorption of ammonia(NH_3-TPD),~(27)Al nuclear magnetic resonance(~(27)Al-NMR)and high-resolution transmission electron microscopy(HRTEM).The results showed that the Si–OH group content of SiO_2 was mainly dependent on the pretreatment conditions and had significant influence on the activity of the Ni Mo catalyst.The surface properties of the aluminated SiO_2 varied with the Al_2O_3-grafting cycles.Generally after four cycles of grafting,the aluminated SiO_2 behaved like amorphous alumina.In addition,plotting of activity of Ni Mo catalysts supported on aluminated meso–macroporous silica materials against the Al_2O_3-grafting cycle yields a volcano curve.     

Study on Preparation and Application of Ti／Si Complex Zeolite

A Ti/Si complex zeolite has been prepared. X-ray diffraction and infrared spectrometry study has shown that two structures, namely the ZSM-5 and MCM-41, exist in the sample. BET tests have revealed that the complex zeolite contains regular mesopores of 2.6 nm. Ultraviolet spectrometry analysis has shown that the Ti species exist in the zeolite skeleton in the form of tetra-coordinate valence. The Ti/Si complex zeolite (TS-1/Ti-MCM-41) has apparently improved catalytic activity with respect to the macromolecular organic compound oxidation as compared to individual components of either Ti or Si containing zeolites (TS-1 and Ti-MCM-41).     

Preparation and Characterization of Pyrotechnics Binder–Coated Nano-Aluminum Composite Particles

The aim of this article is to protect the activity of nano-aluminum (Al) particles in solid rocket propellants and pyrotechnics. The morphology, structure, active aluminum content, and thermal and catalytic properties of the coated samples were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FTIR), thermogravimetry–differential scanning calorimetry (TG-DSC), and oxidation–reduction titration methods. The results indicated that nano-Al particles could be effectively coated with phenolic resin (PF), fluororubber (Viton B), and shellac through a solvent/nonsolvent method. The energetic composite particles have core–shell structures and the thickness of the coating film is about 5–15 nm. Analysis of the active Al content revealed that Viton B coating had a much better protective effect. The TG-DSC results showed that the energy amount and energy release rate of PF-, Viton B–, and shellac-coated Al particles were larger than those of the raw nano-Al particles. The catalytic effects of coated Al particles on the thermal decomposition of ammonium perchlorate (AP) were better than those of raw nano-Al particles, and the effect of shellac-coated Al particles was significantly better than that of Viton B–coated Al particles.     

The study of catalytic performance of silica-supported three metallic Fe–Co–Ce catalyst prepared using impregnation procedure for Fischer–Tropsch synthesis

We apply the wet impregnation procedure to prepare the Fe–Co–Ce catalyst supported by silica. The effects of operational conditions such as temperature, pressure, and the feed ratios of reaction on the selectivity and yield were studied. The production of light olefins from syngas (CO and H₂) over this catalyst in a fixed bed reactor via Fischer–Tropsch synthesis (FTS) was investigated. The reactor tests were determined through the design experiments.The optimum condition was determined in a way that the selectivity of methane was the least and other olefins have the maximum selectivity. The results indicated that the catalyst at 350°C, 3 bar, and syngas with H₂/CO ratio 1/1 has shown the better catalytic performance for FTS.     

Preparation of VPO Catalysts and Effect of Zirconium Promoter on the Selective Oxidation of Pentane

1. Introduction The C5 cut, a relatively low-cost hydrocarbon stream in oil refining, has not found adequate use in petrochemical industry (Weissermel and Arpe, 1978). If it is used as liquid-petroleum-gas (LPG) component, the C5 cut is too heavy; while if it is used as gasoline component, the C5 cut is relatively too light. On the contrary, the demand for phthalic and maleic anhydrides is expected to grow at a rate of about 5% per year (Gleaves and Centi, 1993) due to their increasing app…     

Preparation of an SBS Latex–Modified Bitumen Emulsion and Performance Assessment

Abstract

For resolving the contradiction of the stability between styrene-butadiene-styrene (SBS)-modified bitumen emulsion and the concentration of SBS, a method of preparing SBS latex is provided in this article. Results showed that SBS latex had good stability properties and performance. The effect of emulsifier concentration on the storage stability showed that the maximum stability of SBS latex–modified bitumen emulsion (SBS-LMBE) was obtained at emulsifier weight concentration 1.0% and addition of SBS latex to bitumen emulsion enhanced the difficulty of emulsification. The effects of SBS latex on bitumen properties showed the penetration decreased, whereas the softening point and ductility at 5°C increased, which means that SBS latex plays a role in improving the properties of bitumen. Compared to the base bitumen, saturate and aromatic of evaporation residue of SBS-LMBE decreased. However, resin and asphaltene increased. Analysis of the relationship between the components and properties of bitumen showed that the components change caused by SBS latex was beneficial to the properties of bitumen. The colloidal index (CI) showed that SBS latex also made the colloidal system more stable.     

Study on Preparation and Engine Bench Test of Friction-Reducing and Repairing Additive to Lubricating Oils

A new kind of friction-reducing and repairing additive containing nano-scale copper and rare earth compounds were prepared by means of synthesis and compounding methods. The performance of the said additive was investigated by engine bench test, and was compared to the performance of similar domestic and imported additives. The deterioration of lube oils containing additives over different time intervals was studied by means of plasma spectrometry and mass spectrometry, and the effect of additive package on engine power was also studied. Test results have revealed that the synthetic additive package can provide good anti-wear performance to the tribo-pairs. In particular, after 300 hour application of the said additive package the connection rod shaft and copper sleeve showed ““zero wear““ to achieve the in situ dynamic repairing of tribo-pairs. Application of the said synthetic additive can effectively improve the engine power performance and extend the engine service life.     

Preparation and Characterization of Zeolite Beta with Low SiO_2/Al_2O_3 Ratio

Zeolite beta with a low SiO2/Al2O3 ratio was synthesized by a novel two-step process.The synthesized sample was characterized with XRD,SEM,FTIR,and N2 adsorption-desorption and solid-state MAS NMR.The results showed that aluminium species were inserted into the framework of zeolite beta.The BET surface area,volume,and particle size of the zeolite beta sample decreased with decreasing SiO2/Al2O3 ratio.Our process was proved an efficient route to synthesize zeolite beta with a low SiO2/Al2O3 ratio.     

Effect of the degree of zeolite recrystallization into micro–mesoporous materials on their catalytic properties in petroleum refining and petroleum chemistry processes

It has been shown that by varying the degree of recrystallization of zeolites, it is possible to obtain mesostructured zeolites (RZEO-1), micro–mesoporous nanocomposites (RZEO-2), and mesoporous materials with zeolite fragments (RZEO-3). The main features of the effect of recrystallization degree of MOR, BEA, and FER zeolites on their catalytic properties in the processes of cracking of 1,3,5-triisopropylbenzene, skeletal isomerization of butene-1, hydroisomerization of n-alkanes, alkylation of benzene with dodecene-1, alkylation of naphthalene with cyclohexene, and disproportionation of cumene have been revealed. It has been found that each type of catalytic reaction requires a micro–mesoporous catalyst with an optimal degree of recrystallization. Zeolites RZEO-1 are the most efficient in the reactions that require strong acidity; zeolites RZEO-2 are the most promising in consecutive reactions and reactions that proceed in pore mouths; and RZEO-3 are optimal for transformations of bulky molecules.     

Investigation on performance and emission characteristics of a variable compression multi fuel engine fuelled with Karanja biodiesel–diesel blend

The performance and emission of a single cylinder four stroke variable compression multi fuel engines when fueled with 20%, 25% and 30% of Karanja blended with diesel are investigated and compared with standard diesel. Experiment has been conducted at compression ratios of 15:1, 16:1, 17:1, and 18:1. The impact of compression ratio on fuel consumption, brake thermal efficiency and exhaust gas emissions has been investigated and presented. Experimental analysis on the performance of biodiesel over diesel was evaluated by response surface methodology to find out the optimized working condition. The overall optimum is found to be 25% biodiesel–diesel blended with a compression ratio of 18.     

Study on flame propagation of premixed N2O–NH3/N2O–NH3–C3H8 in cylindrical vessels

The flame propagation behavior of premixed N₂O–NH₃/N₂O–NH₃–C₃H₈ was experimentally investigated in elongated vented cylindrical vessels with central ignition. The effect of vessel diameter and propane concentration ([C₃H₈] = 1.96–7.41 wt.%) on the process of flame acceleration was studied and discussed. The results revealed that the maximum value of flame acceleration rate was found in the cylindrical vessel with an inner diameter of 7 mm, followed by 5 mm, 10 mm, and 15 mm. At a constant vessel diameter, the rate of flame acceleration was noticeably improved by adding propane ([C₃H₈] = 1.96–3.85 wt.%) to the premixed N₂O–NH₃. However, a further increase in the propane fraction up to 5.66%, caused a decline in the flame acceleration rate, probably as a consequence of a combined effect between the reduction of oxygen and greater dilution of the ammonia in the total concentration.     

Fast enrichment and ultrasensitive in-situ detection of pesticide residues on oranges with surface-enhanced Raman spectroscopy based on Au nanoparticles decorated glycidyl methacrylate–ethylene dimethacrylate material

In this study, a fast and ultrasensitive method is proposed for the detection of pesticide residues on oranges. Au nanoparticles (AuNPs) decorated glycidyl methacrylate–ethylene dimethacrylate (GMA–EDMA) powder material served as the solid-phase extraction (SPE) sorbent is synthesized and developed for preconcentration of pesticide residues on oranges and in-situ surface-enhanced Raman spectroscopy (SERS) detection. Here the material is served as not only an enrichment medium but also an enhancement substrate base of the SERS detection. Sample solution is flowed through the material under a vacuum for an enrichment of the analytes and then the concentrated analytes on the material are detected with the Raman spectroscopy. With this method, SERS spectra of phosmet and disulfoton could be identified at concentrations of 5 μg/L and 1 μg/L, respectively. The quantitative curves show linear relationship between Raman intensities and the concentrations of analytes. Furthermore, in real samples detection, phosmet at 8.25 μg/kg and disulfoton at 39.7 μg/kg spiked on oranges can be detected by SERS. Based on the synthesized material and its application in SPE-SERS operation, the method represents ultrasensitive SERS performance in real samples detection with a simple and rapid pre-treatment, which indicates that it could be served as a useful means in monitoring pesticide residues.     

Catalytic performance of dealuminated H–Y zeolite supported bimetallic nanocatalysts in Hydroizomerization of n-hexane and n-heptane

A series of dealuminated Y-zeolites impregnated by 0.5 wt% Pt catalysts promoted by different amounts of Ni, Pd or Cr (0.3 and 0.6 wt%) were prepared and characterized as hydrocracking catalysts. The physicochemical and structural characterization of the solid catalysts were investigated and reported through N₂ physisorption, XRD, TGA-DSC, FT-IR and TEM techniques. Solid catalysts surface acidities were investigated through FT-IR spectroscopy aided by pyridine adsorption. The solid catalytic activities were evaluated through hydroconversion of n-hexane and n-heptane employing micro-catalytic pulse technique directly connected to a gas chromatograph analyzer. The thermal stability of the solids was also investigated up to 800 °C. Crystallinity studies using the XRD technique of all modified samples proved analogous to the parent Y-zeolite, exhibiting nearly an amorphous and microcrystalline character of the second metal oxides. Disclosure of bimetallic catalysts crystalline characterization, through XRD, was not viable. The nitrogen adsorption–desorption isotherms for all samples concluded type I adsorption isotherms, without any hysteresis loop, indicating that the entire pore system is composed of micropores. TEM micrographs of the solid catalysts demonstrate well-dispersed Pt, Ni and Cr nanoparticles having sizes of 2–4 nm and 7–8 nm, respectively. The catalytic activity results indicate that the bimetallic (0.5Pt–0.3Cr)/D18H–Y catalyst is the most active towards n-hexane and n-heptane isomerization while (0.5Pt–0.6Ni)/D18H–Y catalyst can be designed as most suitable as a cracking catalyst.     

The Support Effect on Hydrogenolysis of Thiophene and Gas–Oil

Abstract

Results are reported on the support effect on the catalytic activity in thiophene hydrodesulfurization (HDS) of sulfided Ni-Mo catalysts supported on pure niobia, mixed oxides of Nb₂O₅-TiO₂ prepared by sol-gel method, and Nb₂O₅/TiO₂ and Nb₂O₅/Al₂O₃ prepared by surface deposition. The prepared samples were characterized using N₂ adsorption at ?196°C, X-ray diffraction (XRD), and temperature-programmed reduction (TPR) techniques. This study showed activity variation as a function of support composition. The activity of niobia-rich catalysts was no longer promoted by the synergy between Ni and Mo. The absence of synergy between molybdenum and nickel on niobia can be explained by the strong interaction of each metal with niobia at the expense of interaction with each other. It was found that 5 wt% Nb₂O₅/TiO₂-supported catalyst was the better catalyst for thiophene HDS. It was shown that by means of an adequate support design it is possible to significantly increase the functionalities of HDS catalysts. Semiconducting supports like TiO₂ can improve the HDS activity by exerting electronic effects on the active phase, helping in this way the formation of sulfur vacancies. The 5 wt% Nb₂O₅/TiO₂ was also tested at high pressure with gas oil feedstock. It is observed with the hydrogeolysis of sulfur compounds against time-on-stream that the activity of this catalyst decreases fast with time.     

Preparation of Core-shell Structured Particles and Their Nucleation in Polyester:I. Preparation of Monodisperse SiO_2/PS Core-shell Composite Particles

1. Introduction At present, nanotechnology has been developed intoa new generation of techniques in providing advancedmaterials. This technology now has been applied toprepare and modify macromolecules or polymermaterials through blending, compositing,…     

Comparison of performance of Ni-Mo/γ-alumina catalyst in HDS and HDN reactions of main distillate fractions

A bimetallic nickel-molybdenum catalyst supported on γ-alumina was synthesized by the two-step incipient wetness impregnation technique.The activity of the prepared Ni-Mo/γ-alumina catalyst was evaluated in a down flow fixed-bed microreactor.In this way,hydrodesulfurization(HDS)and hydrodenitrogenation(HDN)reactions of the main distillate fractions of crude oil were assessed.XRD,SEM,TPR,ICP-OES,BET-BJH and nitrogen adsorption/desorption methods were used for characterizing the synthesized Ni-Mo/γ-alumina catalyst.The active metals with Ni/Mo mass ratio of 0.23 and total metal of 13.7 wt% were loaded on the support,similar to the commercial industrial catalyst.The performance tests were conducted at 3.0 MPa(for light naphtha and heavy naphtha)and at 4.5 MPa(for kerosene and gas oil).The results revealed that the total sulfur conversion of the light naphtha,heavy naphtha,kerosene and gas oil fractions was 98.3%,95%,91.7% and 90.1%(after 24 h),respectively.     

Study of the productivity of MWCNT over Fe and Fe–Co catalysts supported on SiO2, Al2O3 and MgO

In the present study, multi-walled carbon nanotubes (MWCNT) were prepared in good quality and quantity, MWCNT were produced using the catalytic chemical vapor deposition (CCVD) technique and the carbon source was acetylene. Different catalysts were synthesized based on iron and a mixture of iron and cobalt metal supported on SiO₂, Al₂O₃ or MgO. The effect of parameters such as iron concentration, support type, bimetallic catalyst and the method of catalyst preparation has been investigated in the production of MWCNT. The quality of as-made nanotubes was investigated by the high-resolution transmission electron microscopy (HRTEM) and thermogravimetric analysis (TGA). The best yield of MWCNT was 30 times of the amount of the used catalyst. The high yield of MWCNT was gained by 40 wt.% Fe on alumina support which was prepared by the sol–gel method. TEM analysis was done for the carbon deposit, which revealed that the walls of the MWCNT were graphitized, with regular inner channel and uniform diameter. It reflected a reasonable degree of purity. The TGA showed that MWCNT was decomposed at 635 °C by a small rate indicating a high thermal stability and well crystalline formation of the produced MWCNT.     

Effect of pH and scale inhibitor concentration on phosphonate–carbonate interaction

In this paper, we present results from five corefloods (RC1 to RC5) from the Jurassic Portlandian limestone (ф ~ 19.80% and k = 606 mD) using 5000 ppm, 10,000 ppm, 25,000 ppm and 27,000 ppm of partly neutralized Diethylenetriamine pentamethylenephosphoric acid (DETPMP) at pH 4 and 2. The purpose of this study was to study the effect of inhibitor concentration and pH on the inhibitor adsorption and on the evolution of the inhibitor and cation (calcium and magnesium) return concentrations. These corefloods were performed using long cores (12 in.), which were treated with just 0.5 pore volume (PV) of inhibitor. Another purpose was to study the transport and inhibitor/carbonate rock interactions when less than 1 PV of inhibitor solution is injected. This allows for consumption of the inhibitor during propagation and return, rather than saturating the core with many PV to full adsorptive capacity of the inhibitor/rock system. This study showed that the higher the concentration of SI and lower the pH, the more calcium dissolution is observed (from the [Ca²⁺] effluents). In all treatments there is a decrease in the [Mg²⁺] effluent corresponding directly to the increase in calcium. The effluent cation results in the long corefloods which strongly support the view that both magnesium and calcium are binding quite strongly to the DETPMP scale inhibitor. These observations lead us to a number of conclusions on the factors that must be included in a full carbonate model. In particular, our experimental results, along with some simple modeling, greatly clarify the role of both calcium and magnesium in the mechanism of the scale inhibitor retention in carbonate systems.