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A novel biodiesel production process using waste cooking oil (WCO) as feedstock was developed in this work. Free fatty acids (FFAs) from WCO were esterified by crude glycerol catalyzed by NaOH, which lowered the content of free fatty acids of WCO. The conversion of FFA in the WCO (acid value: 124.9 mg KOH/g) to acylglycerols is 99.6% under the optimal conditions (1.4:1 molar ratio of glycerol to FFA, 4 h, 210 °C, catalyst loading 0.5 wt.% based on WCO weight). After the transesterification of esterified WCO with methanol catalyzed by NaOH, the yield of the final product is 93.1 wt.% with 98.6 wt.% of fatty acid methyl ester (FAME). The crude glycerol and the catalyst from transesterification were recycled as reactant for esterification during the biodiesel production. Soap formed from the subsequent processes maintained a high catalyzing activity for FFA esterification after being recycled for 13 times. This new glycerol esterification process using alkali (soap) catalyst provides a promising solution to convert feedstock with high FFA levels to biodiesel. This biodiesel production process has distinct advantages compared with traditional two-step methods, including lower cost of catalyst for both esterification and transesterification processes, less energy consumption for methanol recovery, recycling of the glycerol byproduct and catalyst (soap), and no requirement of anti-corrosive equipment.

Fuel-cell-powered APUs (auxiliary power units) are advantageous for on-board electricity supply in heavy trucks, airplanes and ships due to their high efficiency and operation with low emissions. To operate the fuel cells with the fuel available on-board, a desulfurization process is required to avoid the catalyst deactivation in the fuel reforming unit and the fuel cells. The present study aims at developing a modified hydrodesulfurization (HDS) process. The principle underlying this process is the pre-saturation of sulfur-containing fuels with hydrogen-rich reformate. In a pre-saturator, the reformate is mixed with the liquid fuel and compressed to the saturation pressure. This paper presents experimental results demonstrating the desulfurization performance for treating a commercial jet fuel and a high sulfur diesel fuel. A commercial jet fuel with up to 813 ppmw S was desulfurized by a H 2 -containing reformate to a sulfur level under 10 ppmw at an operating temperature in the range of 360 °C to 390 °C and a pressure of 30 bar to 70 bar. Under these conditions a high sulfur diesel fuel was desulfurized to the desired sulfur level as well. A long-term experiment running for up to 602 h verified the durability of the investigated HDS process.

This paper focused on NO x reduction from high volatile pulverized coals by fuel-staged combustion, especially from low rank coal in China with strong slagging tendency, high ash, high moisture, and low calorific value. The results are very important to further enrich the database of fuel-staged combustion. The influences of the main process parameters, including reburn fuel fraction, stoichiometric ratio, residence time in reduction zone, and fuel properties, on NO x emissions were studied experimentally using an Entrained Flow Reactor with Multiple Reaction Segment (EFRM). The present experiments verified that the comprehensive NO x reduction index ( S z ) proposed by the authors for air-staged combustion is still applicable to correlate the maximum NO x reduction rate and coal characteristics in fuel-staged combustion, which would help to predict NO x emissions from fuel-staged combustion more accurately. The experiments also verified that the NO x reduction rate increases with the increase of reburn fuel fraction, with the increase of residence time in reburn zone, and with the decrease of stoichiometric ratio in reburn zone. The results also showed that these parameters have a critical range value, which is 15%–20% for reburn fuel fraction, less than 0.8 for reburn zone stoichiometric ratio, and less than 0.8 s for residence time in reburn zone, respectively. NO x emissions drop with the decrease of the stoichiometric ratio in main combustion zone until it reaches 0.8. For high volatile coals, the effect of fuel-staged combustion on the reduction of NO x emissions increases as the volatile content or fuel-N in the coal increases. The NO x reduction rate increases while the comprehensive NO x reduction index goes up. Moreover, fuel-staged combustion did not significantly reduce the burnout rate of the high volatile coal.

A systematic study was undertaken to investigate the effects of the addition of nickel on the bulk phase composition and reduction/carburization behaviors of a Fe–Ni bimetallic catalyst. The catalyst samples were characterized by powder X-ray diffraction (XRD), transmission electron microscopy (TEM), Mossbauer spectroscopy, X-ray photoelectron spectroscopy (XPS) and H 2 (or CO) temperature-programmed reduction (TPR). The Fischer–Tropsch synthesis (FTS) performance of the catalysts was measured at 1.5 MPa, 250 °C and syngas with H 2 /CO ratio of 2.0. The characterization results indicated that the fresh nickel-promoted catalysts are mainly composed of α-Fe 2 O 3 and NiFe 2 O 4 . The addition of nickel improves the dispersion of iron oxides and decreases the crystallite size of metal oxides. The presence of nickel increases the rates of reduction and carburization in H 2 and CO, respectively, while suppresses the formation of the iron carbides in the syngas reduction. The incorporation of nickel improves the selectivity to methane and suppresses the formation of heavy hydrocarbons (C 5 + ). The catalyst with high nickel content has a high selectivity to methane and low selectivity to heavy hydrocarbons (C 5 + ).

Three kinds of SO3H-functionalized Bronsted-acidic ionic liquids with different acidities were applied to the etherification of glycerol with tert-butyl alcohol. High conversion and good selectivity were obtained under mild conditions. Among the ionic liquids investigated, those having a HSO4− anion afforded the highest glycerol conversion and those having a F3CSO3− anion afforded the largest head product selectivity for glycerol etherification. The minimum-energy geometries and experimental results show that acidities and catalytic activities of ionic liquids are not only related to their structures but also to their immiscibility.

Effects of reducing agents on the textural properties and bulk/surface phase compositions of a precipitated iron-manganese catalyst were investigated by N2-physisorption, X-ray photoelectron spectroscopy (XRD), Mossbauer effect spectroscopy (MES), X-ray photoelectron spectroscopy (XPS) and Raman spectroscopy (LRS). Fischer–Tropsch synthesis (FTS) was performed in a slurry-phase continuously stirred tank reactor. The characterization results indicated that the hematite in the fresh catalyst was converted mainly to magnetite in H2 atmosphere without the formation of intermediate metallic iron. Large amounts of Fe3O4 and small amounts of e′-Fe2.2C and χ-Fe2.5C were formed after syngas pretreatment. In contrast, CO activation led to the formation of large amounts of χ-Fe2.5C and carbonaceous species on the surface of magnetite. In the FTS reaction, the CO-activated catalyst presented the highest initial activity compared to the H2 and syngas-reduced catalysts, and remained unchanged in the activity following the transformation of iron carbides to Fe3O4. Furthermore, the FTS activity of the H2-reduced catalyst increased gradually accompanied with the conversion of magnetite to iron carbides. All of the results suggested that the formation of iron carbides (especially for χ-Fe2.5C) on the surface layers provides probably the active sites for FTS, whereas the Fe3O4 formed plays a negligible role in the FTS activity.

A systematic study was undertaken to investigate the effects of the initial oxidation degree of iron on the bulk phase composition and reduction/carburization behaviors of a Fe–Mn–K/SiO 2 catalyst prepared from ferrous sulfate. The catalyst samples were characterized by powder X-ray diffraction (XRD), Mossbauer spectroscopy, X-ray photoelectron spectroscopy (XPS) and H 2 (or CO) temperature-programmed reduction (TPR). The Fischer–Tropsch synthesis (FTS) performance of the catalysts was studied in a slurry-phase continuously stirred tank reactor (CSTR). The characterization results indicated that the fresh catalysts are mainly composed of α-Fe 2 O 3 and Fe 3 O 4 , and the crystallite size of iron oxides is decreased with the increase of the initial oxidation degree of iron. The catalyst with high content of α-Fe 2 O 3 in its as-prepared state has high content of iron carbides after being reduced in syngas. However, the catalyst with high content of Fe 3 O 4 in its as-prepared state cannot be easily carburized in CO and syngas. FTS reaction study indicates that Fe-05 (Fe 3+ /Fe total = 1.0) has the highest CO conversion, whereas Fe-03 (Fe 3+ /Fe total = 0.55) has the lowest activity. The catalyst with high CO conversion has a high selectivity to gaseous hydrocarbons (C 1 –C 4 ) and low selectivity to heavy hydrocarbons (C 5+ ).

A two-step method is proposed to obtain high selectivity and high conversion rate for producing additive triacetylglycerol of biofuel from its byproduct glycerol. The esterification of glycerol with acetic acid was carried out over resin and zeolites. Amberlyst-35 was found to be an excellent catalyst. The reaction conditions were optimized by testing catalysts, temperatures, feedstock ratios as well as loads of catalysts. The optimal conditions are temperature of 105 °C and an acetic acid to glycerol molar ratio of 9:1 with 0.5 g catalyst. After the 4 hour reaction of the optimal condition, the selectivity of triacetylglycerol reaches almost 100% in 15 min by adding thereto acid anhydride. Recycling experiments indicate that no significant deactivation of Amerlyst-35 occurred during the reaction.

A ceramic membrane separation process for biodiesel refining was developed to reduce the considerable usage of water needed in the conventional water washing process. Crude biodiesel produced by refined palm oil was micro-filtered by ceramic membranes of the pore size of 0.6, 0.2 and 0.1 μm to remove the residual soap and free glycerol, at the transmembrane pressure of 0.15 MPa and temperature of 60 °C. The flux through membrane maintained at 300 L m − 2 h − 1 when the volumetric concentrated ratio reached 4. The content of potassium, sodium, calcium and magnesium in the whole permeate was 1.40, 1.78, 0.81 and 0.20 mg/kg respectively, as determined by inductively coupled plasma-atomic emission spectroscopy. These values are lower than the EN 14538 specifications. The residual free glycerol in the permeate was estimated by water extraction, its value was 0.0108 wt.%. This ceramic membrane technology was a potential environmental process for the refining of biodiesel.

The consecutive phase transformations of a precipitated spray-dried iron-based catalyst for slurry Fischer–Tropsch synthesis (FTS) during activation and reaction process were investigated using Mossbauer effect spectroscopy (MES). It was found that the fresh iron catalyst activation in situ using syngas resulted in the formation of a mixture of iron carbides and superparamagnetic (spm) phases. The relatively small size of fresh iron crystallites was an important factor in the formation of e′-Fe2.2C. During the reduction process, Fe3+ (spm) phase was easier to be reduced than α-Fe2O3 phase. Fe3O4 was not an active phase for FTS. The transformation of α-Fe2O3 into Fe3O4 before carbides formation was necessary to obtain FTS activity of the iron catalyst. There was a correlation between the content of CH4 in tail gas and the amount of iron carbides during activation. It was found that carbonization was the dominating phase transformation when the FTS reaction temperature increased from 250 °C to 270 °C. However, the oxidization was more remarkably at higher FTS reaction temperature. χ-Fe5C2 was the main iron phase at lower reaction temperature. The changes in the bulk compositions resulted in the variation in catalyst activity during FTS. The results of this study showed that the active phase for FTS was a mixture of carbides and corresponding amounts of superparamagnetic phase.

A study has been carried out to investigate the effects of binder SiO2 content on catalytic behavior of spray-dried precipitated Fe/Cu/K/SiO2 catalysts for Fischer–Tropsch synthesis (FTS). The catalysts were characterized by means of N2 physisorption, H2 temperature-programmed reduction (TPR), scanning electron microscopy (SEM), and Mossbauer effect spectroscopy (MES). The Fischer–Tropsch synthesis performances (activity, selectivity and stability) of the catalysts were studied in a slurry-phase continuously stirred tank reactor (CSTR). The results indicated that the increase of SiO2 content stabilizes Fe3O4 phase and suppresses the further reduction and carburization of the catalysts in syngas. Long time on stream FTS performances showed that the catalyst with SiO2 improves its reaction stability. The selectivities to light hydrocarbons (methane, C2–C4, C5–C11) are enhanced whereas those to heavy hydrocarbons (C12+) are suppressed with increasing SiO2 content. The results were explained to the interactions of Fe–SiO2 and K–SiO2. From the present study, it is found that a catalyst with composition of 100Fe/5Cu/4.2K/25SiO2 on mass basis displays both better FTS performances and a good attrition resistance, which is suitable for the use in CSTRs or SBCRs (Slurry Bubble Column Reactors) for FTS reaction.

The preparation and the pretreatment of Pd/ZnO catalysts were studied for methanol steam reforming. The presence of nitric acid in Pd nitrate precursor significantly altered the porosities and crystalline structures of the ZnO support. The dissolution of ZnO and extent of mixing between the Zn 2+ and Pd 2+ cations during catalyst preparation may have an impact on the PdZn alloy formation and its catalytic properties. The pretreatment of Pd/ZnO, which is critical to the PdZn alloy formation, depends not only on the reduction temperature but also on the reaction conditions under which hydrogen is formed.