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 ZSM-5 zeolite and silicalite from rice husk ash

Local rice husk was precleaned and properly heat treated to produce high purity amorphous SiO₂ for use in the synthesis of ZSM-5 zeolite and silicalite by hydrothermal treatment (150 °C) of the precursor gels (pH 11) under autogenous pressure in a short reaction time (4–24 h). A wide range of SiO₂/Al₂O₃ molar ratios (30–2075) and a small template content were employed to fully exploit the potential of rice husk ash (RHA). The mineralogical phases, morphology, specific surface area and pore volume of the synthesized products were investigated by XRD, FT-IR, SEM and BET analyses, respectively. Under the employed conditions, it was found that the gels with a low range of SiO₂/Al₂O₃ molar ratios (<80) produced an amorphous phase to poorly crystalline ZSM-5 zeolite; those with a medium range (80–200) favored well crystalline ZSM-5 zeolite production with a large surface area; whilst those with a high range of SiO₂/Al₂O₃ molar ratios (>200) yielded silicalite. The increase in Na₂O content, which was derived from the addition of NaAlO₂ to attain the desired SiO₂/Al₂O₃ molar ratio of the gel, did not significantly enhance the crystallization rate, crystallinity, or yield of products. On the contrary, these properties were greatly affected by the increase in the SiO₂/Al₂O₃ molar ratio.     

Photocatalytic activity of TiO2 coated porous silica beads on degradation of cumene hydroperoxide

Recently, due to an increasing global concern on environmental safety, titanium dioxide (TiO₂) photocatalyst has been extensively researched for use as air and water pollution treatments. This study was initiative for producing an economically viable TiO₂ photocatalyst material with recyclability for degradation of CHP contaminated wastewater. TiO₂ P‐25, a well‐known photocatalyst, with a proper amount (15% w/w of CAC) was coated on porous silica beads (ECOLITE^®) by granulation technique, using high calcium aluminate cement (CAC) as a binder (EC+CAC+15% w/w TiO₂ P‐25). The experiments revealed that high concentration CHP solutions were completely degraded by EC+CAC+15% w/w TiO₂ P‐25 within 5 and 7 hours. The recyclability of EC+CAC+15% w/w TiO₂ P‐25 was evaluated by investigation the degradation activity of freshly prepared CHP solution under UV light irradiation using the repetitive photocatalyst beads for 6 runs. HPLC analyses indicated that the CHP degradation was completed in the 1^st run and down to over 90% in the 6^th run. Hence, EC+CAC+15% w/w TiO₂ P‐25 showed a long durability and good recyclability for CHP degradation, resulted from the good adherence of hydration product layer of CAC for TiO₂ particles as well as its large surface area that offered good adsorption for CHP.     

Photocatalytic activity of TiO2/ZSM-5 composites in the presence of SO4 ion

TiO₂/ZSM-5 composites were prepared from SiO₂ of rice husk ash and TiO₂ sol from hydrolyzed TiOSO₄ salt. The combined effect of these two materials greatly enhanced the photocatalytic decolorization of methylene blue dye solution. The instant decolorization of the dye solution in the dark by the composite, TiO₂/ZSM-5 (wt ratio 1:1), resulted from the combination of the adsorption by ZSM-5 zeolite and TiO₂ nano-particles, and of Na₂SO₄ salt adhering to the composite surface. As a strong flocculating agent, the SO₄²⁻ ion caused the precipitation of the dye onto the composite surface which consequently enhanced the photocatalytic decolorization of the dye under UV irradiation. The composite, TiO₂/ZSM-5 (wt ratio 1:5), completely decolorized the methylene blue dye in 2.5 h, giving an equivalent performance to that of TiO₂, P-25 powder.