Ultrasound-assisted Oxidative Desulfurization Process Research Articles

Synthesis and characterization of phosphotungstic acid/activated carbon as a novel ultrasound oxidative desulfurization catalyst

Phosphotungstic acid/activated carbon (PTA/AC) catalysts with various AC sizes or PTA content have been synthesized and characterized by N2 physisorption, X-ray diffraction, Fourier transform infrared spectroscopy and temperature programmed desorption of ammonia. These catalysts were then evaluated in terms of the removal of dibenzothiophene (DBT) by ultrasoundassisted oxidative desulfurization process. The results showed that the DBT conversion obviously increased with the decrease of AC support size and the increase of PTA content. After supporting PTA on AC, the DBT conversion can be improved by 38.9% after ultrasound irradiation for 10 min. In addition, the stability tests of PTA/AC showed that the catalytic oxidative activity of PTA/AC was nearly kept constant after ultrasound irradiation for 20 min, which makes it a promising catalyst to use in ultrasound-assisted oxidative desulfurization process.

Sulfur removal of gas oil using ultrasound-assisted catalytic oxidative process and study of its optimum conditions

Ultrasound-assisted oxidative desulfurization process (UAOD) was applied to reduce sulfur compounds of gas oil containing various types of sulfur content. The environmental regulation requires a very deep desulfurization to eliminate the sulfur compounds. UAOD is a promising technology with lower operating cost and higher safety and environmental protection. For the first time the typical phase transfer agent (tetraoctyl-ammonium-bromide) was replaced with isobutanol because using isobutanol is much more economical than TOAB, imposing no contamination. The reaction was carried out at optimal point with various temperatures, in single-, two- and three step-procedures, investigating the effect of gradual increase of H2O2 and TOAB being used instead of isobutanol. Total sulfur concentration in oil phase was analyzed by ASTM-D3120 method. The highest removal of about 90% for gas oil containing 9,500 mg/kg of sulfur was achieved in three-steps during 17 minutes of process at 62±2 °C when 180.3 mmol of H2O2 was used and extraction carried out by methanol.

An economic analysis of the continuous ultrasound-assisted oxidative desulfurization process applied to oil recovered from waste tires

Abstract A cost–benefit analysis of the ultrasound-assisted oxidative desulfurization (UAOD) continuous-flow process in organic sulfur removal from pyrolysis oil was carried out. Two separate studies using one and two UAOD units were compared by cost and percentage of sulfur removal. The desulfurization cost for a single UAOD unit was calculated at $0.70/gal with sulfur removal of 68%, whereas the cost and removal percentage were $1.39/gal and 90.91%, respectively, for two UAOD units connected in a series. The monetary value of the health benefits was around $466.59/d for one unit and $623.78/d for two units. Moreover, the best gross income for desulfurized pyrolysis oil after the UAOD system was $1916.46/d in Taiwan. Economic and risk evaluations demonstrated that pyrolysis oil desulfurization using one set of UAOD continuous-flow units can provide full benefits and has few environmental or health impacts.

Optimization of Thiophene Removal by an Ultrasound-Assisted Oxidative Desulfurization Process

Abstract Thiophene (T) is considered one of the most refractory organic sulfur compounds in oxidative desulfurization. This study used an ultrasound-assisted oxidative desulfurization process to optimize T oxidation on a bench scale. Four control factors, including durations of sonication, the amounts of transition metal catalyst (TMC), phase transfer agent (PTA), and hydrogen peroxide, were carefully examined. The best operation condition, evaluated by using the analysis of variance, was found at mass ratios of T:H2O2:PTA:TMC at 1:1.5:0.005:0.01 with 20 min of sonication, where almost 73.5% of T, 89.9% of benzothiophene (BT), and 100% of dibenzothiophene (DBT) were oxidized to their corresponding sulfones. Moreover, the electron density on the sulfur atom of various compounds, including T, BT, and DBT, and their methyl-substituted derivatives and oxidation rate constants were also examined. The oxidative reactivity of sulfur compounds increased with the increasing electron density on sulfur atoms. The T ...

Sulfur removal from hydrotreated petroleum fractions using ultrasound-assisted oxidative desulfurization process

Ultrasound-assisted oxidative desulfurization (UAOD) process was applied to diesel oil and petroleum product feedstock containing model sulfur compounds (benzothiophene, dibenzothiophene and dimethyldibenzothiophene). The influence of oxidant amount, volume of solvent for the extraction step and time and temperature of ultrasound treatment (20kHz, 750W, operating at 40%) was investigated. Using the optimized conditions for UAOD, sulfur removal up to 99% was achieved for model compounds in petroleum product feedstock using a molar proportion for H2O2:acetic acid:sulfur of 64:300:1, after 9min of ultrasound treatment at 90°C, followed by extraction with methanol (optimized solvent and oil ratio of 0.36). Using the same reagent amount and 9min of ultrasound the removal of sulfur was higher than 75% for diesel oil samples. Sulfur removal without ultrasound using the same conditions was lower than 82% for model compounds and 55% for diesel oil samples showing that ultrasound improved the efficiency of oxidative desulfurization. In comparison to conventional hydrodesulfurization, the proposed UAOD process can be performed under relatively mild conditions (atmospheric pressure and 90°C, without using metallic catalysts).

The study of ultrasound-assisted oxidative desulfurization process applied to the utilization of pyrolysis oil from waste tires

In recent years, the increasing world population and rapid industrial development has increased the consumption of fossil fuel-derived oils. In response to the resulting exhaustion of fossil fuel energy, many countries around the world are investigating methods of waste energy recovery and reuse, including oil recovery from the pyrolysis process of waste tires. This study investigates the efficiency of an ultrasound-assisted oxidative desulfurization (UAOD) process in sulfur reduction from diesel oil and the pyrolysis oil from waste tires treatment. The results indicate that the oxidation efficiency increases as the doses of transition metal catalyst are increased. Longer sonication time also enhances the oxidation process, apparently through the biphasic transfer of oxidants, which results in a high yield of organic sulfur oxidation products. The best desulfurization efficiency was 99.7% (2.67 ppm sulfur remaining) and 89% (800 ppm sulfur remaining) for diesel and pyrolysis oils, respectively, via a process executed by two UAOD units connected in series and combined with solid adsorption using 30 g of Al 2O 3 in 6 cm columns. These batch experiment results demonstrate clean waste energy recovery and utilization, while fulfilling the requirements of Taiwan EPA environmental regulations (sulfur concentrations less than 5000 ppm).

Ultrasound-assisted oxidative desulfurization of liquid fuels and its industrial application

Latest environmental regulations require a very deep desulfurization to meet the ultra-low sulfur diesel (ULSD, 15 ppm sulfur) specifications. Due to the disadvantages of hydrotreating technology on the slashing production conditions, costs and safety as well as environmental protection, the ultrasound-assisted oxidative desulfurization (UAOD) as an alternative technology has been developed. UAOD process selectively oxidizes sulfur in common thiophenes in diesel to sulfoxides and sulfones which can be removed via selective adsorption or extractant. SulphCo has successfully used a 5000 barrel/day mobile “Sonocracking” unit to duplicate on a commercial scale its proprietary process that applies ultrasonics at relatively low temperatures and pressures. The UAOD technology estimate capital costs less than half the cost of a new high-pressure hydrotreater. The physical and chemical mechanisms of UAOD process are illustrated, and the effective factors, such as ultrasonic frequency and power, oxidants, catalysts, phase-transfer agent, extractant and adsorbent, on reaction kinetics and product recovery are discussed in this review.

Surface characterization of adsorbents in ultrasound-assisted oxidative desulfurization process of fossil fuels

Surface properties of two different phases of alumina were studied through SEM images. Characterization of amorphous acidic alumina and crystalline boehmite by XRD explains the differences in adsorption capacities of each sample. Data from small angle neutron scattering (SANS) provide further results regarding the ordering in amorphous and crystalline samples of alumina. Quantitative measurements from SANS are used for pore size calculations. Higher disorder provides more topological traps, irregularities, and hidden grooves for higher adsorption capacity. An isotherm model was derived for adsorption of dibenzothiophene sulfone (DBTO) by amorphous acidic alumina to predict and calculate the adsorption of sulfur compounds. The Langmuir–Freundlich model covers a wide range of sulfur concentrations. Experiments prove that amorphous acidic alumina is the adsorbent of choice for selective adsorption in the ultrasound-assisted oxidative desulfurization (UAOD) process to produce ultra-low-sulfur fuel (ULSF).

Selective Adsorption in Ultrasound-Assisted Oxidative Desulfurization Process for Fuel Cell Reformer Applications

Alumina has been used as a selective solid adsorbent for a scaleup test of a jet fuel and diesel fuel desulfurization technique. The oxidative process with ultrasound assistance has been improved f...