Guo Xian Yu

Removal of dibenzothiophene in diesel oil by oxidation over a promoted activated carbon catalyst

Oxidative removal of dibenzothiophene (DBT) in n-octane solution by H2O2 on a promoted activated carbon (AC) catalyst was studied. DBT adsorption and catalytic behaviors on AC were examined. Effects of pH in aqueous phase, amounts of AC and formic acid (HCOOH) for promotion as well as initial molar H2O2/S ratio were investigated. Experimental results led to conclusion that DBT was readily oxidized by H2O2 over an AC catalyst promoted by HCOOH. Suitable amount of AC can improve the activity of H2O2 resulting in a deeper extent of sulfur removal. A 100% conversion of DBT in an octane solution by H2O2 oxidation was attained on the HCOOH-H2O2/AC catalyst at 80°C for a reaction time of 30 min.

Adsorption of Dibenzothiophene on Transition Metals Loaded Activated Carbon

Transition metal-modified carbon-based adsorbents were prepared by impregnating activated carbon with solutions of copper, cobalt or nickel chloride or nitrate. The mixtures were dried and then calcined under nitrogen stream. The surface metal species were analyzed by XRD technique and the surface oxygen-containing groups were characterized by FTIR. Their adsorption capacities for dibenzothiophene (DBT) were measured by using DBT-containing n-octane solution as model oil. Experimental results show that the metal species on the carbon surface could be controlled by the calcination process under nitrogen atmosphere. Both the transition metal precursors and kinds of metal species on the carbon surface have significant effects on DBT adsorption capacity.

Performance of Sodium Chlorite/Urea on Simultaneous Desulfurization and Denitrification in a Rotating Packed Bed

Performance of simultaneous desulfurization and denitrification from N2-NO-SO2 simulated flue gas using sodium chlorite as the additive and urea as the reductant in a rotating packed bed was investigated. In RPB, various rotational speeds, the flow rates of SO2, the flow rates of NO and the liquid flow rates were studied by means of the calculation of the removal efficiencies of SO2 and NO. The experimental results showed that the removal efficiency of SO2 was higher than 99.00% under various experimental conditions, while the removal efficiency of NO exhibited different results. A better simultaneous desulfurization and denitrification behavior could be obtained under the conditions of a SO2-NO-N2 simulated flue gas with the ratio of SO2/NO/ N2=6:4:8.33(v), a rotational speed of 460 rpm and an absorbent flow rate of 120 L/h.

Simulation of Delayed Coking Reaction in Coke Drum

Abstract The effect of basic operating variables and technologies on reaction behaviors during the whole coking half cycle of an empty coke drum in three industrial delayed coking units was examined. It was observed that the temperature of the liquid streams and yields for gasoline and diesel oil in the coke drum were all stable after a few hours. Since then it was demonstrated that the coke drum was operated like a steady-state flow-type stirred-tank reactor (STR). These results will pave the way for the theoretical calculation of the coke drum for simulation and prediction.

Adsorptive Removal of Dibenzothiophene in Diesel Fuel on an Adsorbent from Rice Hull Activated by Phosphoric Acid

Rice hull (designated with RH) was activated by phosphoric acid to prepare an adsorbent for the removal of sulfur-containing compounds from diesel fuel. Adsorption tests for both, a 300 µg.g-1 dibenzothiophene (DBT)-containing n-octane solution using as model oil and a commercial hydro-treated diesel fuel, were performed to elucidate the effect of varying phosphoric acid to RH ratio, treating temperature and the removal of silica from the adsorbent on the combination of the textural structure, surface chemical property and adsorption capacity. It was indicated that high surface area and micro-pore volume of the adsorbent favored the adsorption of DBT and its derivatives. Richening of oxygen-containing compounds on the adsorbent surface was advantageous to the adsorption and removal of DBTs. At a phosphoric acid and RH weight ratio of 3:1 by using a two-step treatment, a satisfactory adsorbent with an adsorption capacity of 28.89 mg S/g was successfully prepared. If the silica in the adsorbent was further removed, the product exhibited the highest performance, reaching 30.43 mg S/g for the model oil and 21.79 mg S/g for the commercial diesel fuel. Both the textural structure and the surface chemical property like acidic groups of a RH-based adsorbent play important roles in its adsorption behaviors, and the formation of donor-acceptor complexes between surface acidic groups and DBT may probably benefit DBT adsorption capacity.

Oxidative Removal of Dibenzothiophene by H2O2 over Activated Carbon-Supported Phosphotungstic Acid Catalysts

Phosphotungstic acid (HPW) supported on activated carbon (AC) combined with hydrogen peroxide formed an oxidative desulfurizaiton (ODS) system to oxidize sulfur-containing compounds in diesel fuel. Dibenzothiophene (DBT) dissolved in n-octane was selected as a model feedstock for studying this new ODS system. The HPW/AC catalysts were characterized with XRD, FTIR and N2 adsorption-desorption measurements. HPW was highly dispersed on the surface of carbon support. It was found that the DBT adsorption capacity decreased from 42 mg S/g to 33.13 mg S/g as HPW loading amount increased from 0 to 15 wt.%. Oxidative removal of DBT in the model oil significantly increased with increasing HPW loadings on the support from 0 to 10 wt.%. 100 % DBT was removed by using the catalysts with HPW content higher than 10 wt. %. At 80 °C, oxidative removal of DBT reached 100 % after 40 min of reaction when O/S molar ratio ranged from 4 to 10.

Effect of Surface Modifier on their Tribological Properties of LaF3 Nanoparticles in Base Oil

Surface modifiers with different lipophilic chain lengths, such as, lauric acid diethanolamine, myristic acid diethanolamine, palmitic acid diethanolamine and stearic acid diethanolamine, were used to prepare four kinds of LaF3 nanoparticles in the mixture solvent of water-ethanol. Morphology and surface modification of LaF3 nanoparticles were investigated by TEM, FTIR and TG. Effect of length of surface modifier lipophilic chain on tribological properties of LaF3 nanoparticles and their susceptibility to base oils were investigated by a four-ball machine. Results show that the tribological properties of LaF3 nanoparticles in the base oil in build up as lipophilic chain length of surface modifiers increases; the longer the lipophilic chain is, the better the susceptibility of the nanoparticles to liquid paraffin wax is. This is mainly because that the lipophilic chain length influences the interface activity of the nanoparticles, moreover, for homologous organic acid soaps, the longer the lipophilic chain is, the better its friction reducing performance is; the properties of base oils also influence the interface activity of the nanoparticles.

CO2 Capturing by MDEA-PZ-TETA in a Rotating Packed Bed

The absorption performance of CO2 using MDEA-PZ-TETA ternary absorbent in a rotating packed bed was investigated. The effects of the concentration of the ternary absorbent, the absorbing liquid temperature, the rotating speed, the liquid flow rate and gas flow rate on the absorption performance of CO2 were discussed in detail. The experimental results showed that the optimum absorption condition was the absorbent concentration of 0.05 mol/L, the absorption temperature of 290 K, the rotating speed of 454 rpm and the ratio of gas to liquid of 1.2, which could provide a molar absorption saturated capacity of 1.3688 molCO2/molAm and a satisfying CO2 absorptivity of 93.18%.

Simultaneous Absorption of SO2 and NO Using Sodium Chlorate/Urea Absorbent in a Rotating Packed Bed

In this work, simultaneous absorption of SO2 and NO from N2-NO-SO2 simulated flue gas using sodium chlorate as the additive and urea as the reductant was investigated experimentally in a rotating packed bed. In RPB, various rotational speeds, gas flow rates and liquid flow rates were studied by means of the removal efficiency of SO2 and NO. The experimental results showed that the removal efficiency of SO2 was higher than 99.00% under various experimental conditions and, at the same time, the removal efficiency of NO exhibited different results under various experimental conditions. The simultaneous NO removal efficiency of 82.45% and the SO2 removal efficiency of 99.49% could be obtained under the N2 flow rate of 0.5 m3/h, SO2 flow rate of 6 mL/min, the NO flow rate of 4 mL/min, the rotational speed of 460 rpm and the absorbent flow rate of 40 L/h.

Effect of Steam on the Reaction Performance of Oxidative Dehydrogenation of Cyclohexane

The effect of steam, fed to the fixed-bed microreactor reactor, on the oxidative dehydrogenation of cyclohexane over Mg3(VO4)2 catalyst was reported. The catalyst characterization results showed that the crystal structure, the electron cloud distributions of the active species and the oxygen species, and the reducibility of the active species are not influence by the introduction of steam. It was observed that steam added to the oxidative dehydrogenation of cyclohexane competes for sites required for gas-phase oxygen activation, which catalyst lattice oxygen utilization is not affected. The shorter residence time and the competition for sites with oxygen causes a decrease in cyclohexane conversion and a corresponding increase in selectivity to cyclohexene.