Conversion of used vegetable oils to liquid fuels and chemicals over HZSM-5, sulfated zirconia and hybrid catalysts

Thailand’s food manufacturing uses about 47 Million liters per year of vegetable oil. Used vegetable oil is classified as waste, but has potential for conversion into liquid fuel. This research studied the catalytic conversion of used vegetable oil to liquid fuel, where investigation was performed in a batch microreactor over a temperature range of 380–430 °C, initial pressure of hydrogen gas over 10–20 bars, and reaction time of 45–90 minutes. Catalysts such as HZSM-5, Sulfated Zirconia and hybrid of HZSM-5 with Sulfated Zirconia were used to determine the conversion and yield of gasoline fraction. The major products obtained were liquid products, hydrocarbon gases and small amounts of solids. Liquid products were analyzed by simulated distillation gas chromatograph and the product distribution was obtained. Hybrid catalyst HZSM-5 with Sulfated Zirconia showed the highest yield of gasoline with a 26.57 wt% at a temperature of 430 °C, initial hydrogen pressure at 10 bars, and reaction time of 90 minutes in the ratio of hybrid HZSM-5 with Sulfated Zirconia at 0.3: 0.7.     

Synthesis of char,bio-oil and gases using a screw feeder pyrolysis reactor

In this study, char, bio-oil and gases were synthesized with a continuous pyrolysis process from residual plants consisting of Cogongrass and Manilagrass at temperatures in the range of 400–550°C, with a feed rate of 150, 350, and 550 rpm (r min^?1). The product yield calculation showed that the liquid yield was highest at 53.56%, at 350 rpm. After separation of the bio-oil from liquid phase, the bio-oil was found to have components of approximately 33.38%, of which the solid yield (char) was highest at 27.35%, at 350 rpm, and the gas yield was highest at 43.60%, at 150 rpm. This indicates that biomass from residual plants materials produced good yields because of low solid and gas yields while having high liquid yield.     

Development of a new low-temperature methanol synthesis process

A new reaction route of methanol synthesis at low temperature from CO₂-containing syngas with Cu/ZnO catalyst and the aid of alcohols has been developed in a batch and a flow-type semi-batch reactors. The use of alcohols as catalytic solvents realized methanol synthesis at 443 K with formate as an intermediate. The activity of methanol synthesis depends on types and structures of alcohols. Among all alcohols, 2-alcohol exhibited the highest activity. With the aid of 2-butanol, the one-pass 47.0% conversion and 98.9% selectivity were achieved at a mild condition, 443 K and 50 bar. The new reaction route of methanol synthesis is a practical method for near future technology.     

Production of pure ethanol from azeotropic solution by pressure swing adsorption

Pressure swing adsorption (PSA) is attractive for final separation in the process of water removal especially for fuel ethanol production. Despite many researches on simulation and experimental works on adsorption of water on 3A zeolite in a fixed bed, none have studied a process with the actual PSA system. The purpose of this research was to study the PSA process with two adsorbers and effects of several parameters. The research also included analysis of kinetic and thermodynamic data of ethanol-water adsorption on commercial 3A zeolites in a single fixed bed. A two-level factorial design experiment was used in this research work to preliminarily screen the influence and interaction among the factors. Effects of important parameters such as initial temperature, feed concentration and feed rate were investigated. It was proven that the Langmuir isotherm could best predict the experimental results. In the PSA pilot test, the principal factors, which had effects on the performance, were feed rate, feed concentration, adsorption pressure and the cycle time. Prediction of the process efficiency in terms of ethanol recovery and enrichment was proposed in the form of regression models. The results of the study in a fixed bed adsorber could help designing a pilot-scale PSA unit. The experiments proved to be successful in terms of producing high concentration ethanol with high percentage of ethanol recovery. With further simulation work the process could be scaled up for an industrial use.     

TiO2 promoted Co/SiO2 catalysts for Fischer–Tropsch synthesis

The addition of small amount of TiO₂ to silica-supported cobalt catalysts significantly increasing the dispersion of cobalt and Co metallic surface area resulting in the remarkable enhancement of the Fisher–Tropsch synthesis (FTS) activity in the slurry-phase reaction. The addition of TiO₂ adjusted the interaction between cobalt and silica support quite well to realize the favorite dispersion and reduction degree of supported cobalt, leading to high catalytic activity in FTS. The properties of various catalysts were characterized by in-situ DRIFT, XRD, TPR, N₂ physisorption and H₂ chemisorption.     

Economic assessment of biogas-to-electricity generation system with H2S removal by activated carbon in small pig farm

This study was conducted to assess the economic feasibility of electricity generation from biogas in small pig farms with and without the H₂S removal prior to biogas utilisation. The 2% potassium iodide (KI) impregnated activated carbon selected as H₂S adsorbent was introduced to a biogas-to-electricity generation system in a small pig farm in Thailand as a case study. With the average inlet H₂S concentration of about 2400 ppm to the adsorption unit, the H₂S removal efficiency could reach 100% with the adsorption capacity of 0.062 kg of H₂S/kg of adsorbent. Under the reference scenario (i.e., 45% subsidy on digester installation and fixed electricity price at 0.06 Euro/kWh) and based on an assumption that the biogas was fully utilised for electricity generation in the system, the payback period for the system without H₂S removal was about 4 years. With H₂S removal, the payback period was within the economic life of digester but almost twice that of the case without H₂S removal. The impact of electricity price could be clearly seen for the case of treated biogas. At the electricity price fixed at 0.07 Euro/kWh, the payback period for the case of treated biogas was reduced to about 5.5 years, with a trend to decrease at higher electricity prices. For both treated and untreated biogas, the governmental subsidy was the important factor determining the economics of the biogas-to-electricity systems. Without subsidy, the payback period increased to almost 7 years and about 11 years for the case of untreated and treated biogas, respectively, at the reference electricity price. Although the H₂S removal added high operation cost to the system, it is still highly recommended not only for preventing engine corrosion but also for the environment benefit in which air pollution by H₂S/SO₂ emission and impact on human health could be potentially reduced.     

Effects of promoters on biomass gasification using nickel/dolomite catalyst

Metallic nickel has been selected as a catalyst for biomass gasification because of its activity in biomass steam gasification and tar reduction. The effects of types of promoters such as platinum, cobalt, and iron on biomass gasification were evaluated. The area of interest was the effects of preparation methods, which were impregnation and coprecipitation. Catalyst preparation by the impregnation method showed superior performance. The conclusion can be drawn from the experiments that the platinum promoter enhanced the reforming reaction, iron promoted a water-gas shift reaction, and the cobalt promoter favored a methanation reaction. Moreover, the addition of noble metal reduced carbon deposition on Ni/dolomite.     

Catalytically active supercritical fluid to accelerate methanol synthesis

Supercritical phase 2-butanol significantly increased the conversion of methanol synthesis from syngas not only by the conventional promotion effect of supercritical fluid but also by the catalytic effect of 2-butanol solvent itself, breaking through the thermodynamic limitation of this reaction effectively.     

A Novel, Low Temperature Synthesis Method of Dimethyl Ether Over Cu–Zn Catalyst Based on Self-Catalysis Effect of Methanol

A new DME synthesis route from syngas at a relatively low temperature (443 K) has been developed for the first time by the combination of a conventional DME synthesis catalyst (Cu/ZnO:HZSM-5 catalyst) with methanol as a catalytic solvent. The addition of methanol to the reaction system is the key to the success of DME synthesis at this temperature. Indeed, a CO conversion of 29 and 43% with a DME selectivity of 69 and 68% were achieved at 443 or 453 K, respectively, and 4 MPa, when methanol was used as a catalytic solvent. Importantly, no other by-products including methanol and hydrocarbons were observed in the DME product attained, suggesting no significant subsequent purification stages. Assuming no scale up problems, this process potentially provides a high purity of DME with less energy consumption, and so offers an opportunity for the economically viable future sustainable production of DME.     

Highly efficient sulfur and coking resistance catalysts for tar gasification with steam

Ni-on-dolomite catalysts were found to be effective catalysts for coking resistance and promising sulfur tolerance for steam reforming of tar. Experiments were carried out in a fixed bed reactor at 730–850 °C with a short contact time (W/F: 0.55 g h/mol) and under atmospheric pressure. Toluene and naphthalene were selected as the model component of tar. The process variables such as calcination temperature, reaction temperature and the content of nickel had substantial influence on promising sulfur tolerance in catalytic tar removal by Ni/Dolomite catalysts. Results were compared with the Ni/Al₂O₃, Ni/SiO₂ as a representative of commercial catalysts. The novel 15%Ni/Dolomite almost gasified tar component even at 770 °C and the presence of 100 ppm H₂S in the feed. The poisoning effect of H₂S was discovered to be reversible. The suppression of the catalytic activity by adding H₂S was much lower for Ni/Dolomite than Ni/Al₂O₃. The TGA–DTA analysis of used catalysts revealed that Ni/Dolomite exhibited high resistance to coke deposition over those of the Ni/Al₂O₃, Ni/SiO₂.