Mildly hydrothermal reaction using solid acid catalysts for cellulose hydrolysis into glucose has potential abilities to be one of the key technologies for a future sustainable society using cellulose biomass. Among the solid acid catalysts tested, such as H-form zeolite catalysts and sulfated and sulfonated catalysts, sulfonated activated-carbon (AC–SO3H) catalyst showed remarkably high yield of glucose in the hydrolysis of cellulose with β-1,4-glycosidic bonds under hydrothermal conditions at temperatures around 423 K. The AC–SO3H catalyst with hydrothermal pre-treatment had excellent catalytic properties attributed to the high hydrothermal stability and the strong acid sites of the sulfo functional groups and the activated carbon surfaces for polysaccharide adsorption. A bifunctional sulfonated activated-carbon supported platinum (Pt/AC–SO3H) was prepared by impregnation of platinum on activated carbon (AC) and sulfonation of the prepared Pt/AC. Gluconic acid was produced from polysaccharides, such as starch and cellobiose, in water at 393 K under air by a one-pot process using the Pt/AC–SO3H catalyst.
The development of Ir/SiO2-based catalysts for the selective reduction of NO with CO in the presence of O2 is described in this review paper. The catalytic activity of Ir/SiO2 was promoted considerably by addition of Nb2O5 and WO3. These promoted catalysts showed NO reduction activity even in the absence of SO2, in contrast to Ir/SiO2 catalyst. The addition of Nb2O5 was found to stabilize Ir metal as the active species for NO reduction. Also in the case of WO3, it was concluded that Ir metal interacting strongly with WO3 (denoted as Ir–WO3) is the catalytic active species. High temperature calcination created preferentially the Ir–WO3 species. The catalytic activity and durability of Ir/WO3/SiO2 was further promoted by addition of Ba. The developed Ba/Ir/WO3/SiO2 catalyst in monolithic form showed good performance for NO reduction for actual diesel exhaust.
To investigate the synthesis of isoparaffin from heavy naphtha, n-heptane conversion was studied. Applying and improving the isomerization catalyst developed for n-hexane was examined for n-heptane. The developed catalyst, Pd/nano-sized (defined as 5-50 nm, and here called as ns) Al2O3/H-BEA zeolite, was effective for the isomerization of both n-hexane and n-heptane, but n-heptane was more easily decomposed in comparison with n-hexane. In the case of n-heptane, cracking product selectivity was extremely high at about 85 % at 300 °C. However, improved high activity and selectivity were obtained by removal of residual chlorine from the catalyst, which decreased the number of acid sites acting as cracking sites formed by residual chlorine on ns Al2O3. If the content of ns Al2O3 combined to H-BEA zeolite changed in the catalyst, cracking selectivity remained constant at a lower level comparing with the non-combined zeolite. ns Al2O3 also reduced the acidity of strong acid sites on the zeolite particle surface. X-ray photoelectron spectroscopy showed that reduced Pd/ns Al2O3/H-BEA catalyst with removed residual chlorines had the highest Pd dispersion because the chloride anions act effectively for cationic Pd dispersion on ns Al2O3 which can adsorb chloride anions. Since ns Al2O3 was also highly dispersed onto the zeolite particle surface, acid sites were formed at the boundary. The catalyst has highly dispersed Pd metal because of the stable Pd was highly dispersed on the acid sites by removing chlorine.
The effects of the support on active site formation and hydrodesulfurization (HDS) activity of Rh2P catalyst were examined, using metal oxides (MOx), such as SiO2, TiO2, Al2O3, MgO and ZrO2, as the support. Rh2P was formed on MOx support after reduction of supported rhodium and phosphorus (Rh–P) catalysts. However, differences in the formation temperatures of Rh2P were observed by changing the MOx support. Furthermore, the HDS activities of the supported Rh–P catalysts strongly changed with higher reduction temperature. The order of HDS activities of Rh–P/MOx catalysts reduced at optimal temperatures was SiO2 ∼ TiO2 ∼ Al2O3 > MgO > ZrO2. The TOF of Rh–P/MOx catalysts was enhanced by increasing the reduction temperature to form Rh2P. The order of TOF of supported Rh2P catalysts was TiO2 > ZrO2 > Al2O3 > SiO2 > MgO, and this order disagreed with that of thiophene conversion. The high TOF of Rh–P/TiO2 catalyst may be explained by formation of partially sulfided TiO2 in the HDS reaction. The low TOF of Rh–P/MgO catalyst was attributed to the basicity of the support with low sulfur tolerance.
Beta zeolite (BEA) samples with different SiO2/Al2O3 ratios were synthesized by the dry gel conversion method (DGC) using tetraethyl ammonium hydroxide (TEAOH) as a structure directing agent (SDA). Catalytic properties of BEA for the isomerization and cracking of hexane were evaluated by comparing with the typical zeolites, mordenite (MOR), ZSM-5 (MFI), and ZSM-22 (MWW) with SiO2/Al2O3 ratios of 30-40. The combined selectivities for branched alkanes (2- and 3-methylpentanes, and 2,2- and 2,3-dimethylbutane (b-C6), 2- and 3-methylbutanes, 2,2-dimethylpropane (b-C5), and 2-methylpropane (b-C4)) were highly dependent on the type of zeolites, and decreased in the order: BEA > MWW >> MFI. BEA had the highest activity and selectivity for the isomerization, and MFI had the highest activity and selectivity for cracking to lower alkanes and alkenes. These differences were ascribed to the differences in pore structure, acid properties, and reaction parameters, resulting in the high performance for the isomerization and cracking over BEA with wide channels and weak acidity. The effects of SiO2/Al2O3 ratio of BEA were examined in the isomerization of hexane. The combined selectivity for branched alkanes was almost constant with increase in the SiO2/Al2O3 ratio; however, the selectivity for b-C5 and b-C4 decreased with the increase in the ratio, resulting in increased selectivity for b-C6. These findings indicate that the selectivity for the isomerization was not affected by acid amounts; however, the cracking of isomerized products was enhanced by the increased acid amounts. Catalytic activity and selectivity for branched alkanes remained in the similar level during the reaction using catalysts with the same acid amounts. These results suggest that the acid sites on BEA with different SiO2/Al2O3 ratio prepared by DGC method have uniform and discrete activity with selectivity for the isomerization.
Sulfur reference material for the calibration of sulfur in liquid fuels at trace level, NMIJ RM 4216-a, have been issued by National Metrology Institute of Japan, National Institute of Advanced Industrial Science and Technology (NMIJ, AIST). Toluene was selected for the candidate reference material. The sulfur reference value of this reference material was determined by analysis of the candidate reference material in ampules. The sulfur reference value is 19 μg · kg−1 and the expanded uncertainty (k = 2) is 5 μg · kg−1. The measurement of trace sulfur in the sample was performed using the combustion followed by the ultraviolet fluorescence method. The standard addition method based on the precise gravimetric mixing was applied in the determination.
Maintenance of crude oil storage tanks requires periodical washing of the tanks before ordinary repairs can be made to these systems. In this study, crude oil derived sludge in the oil storage tank was treated with various surfactants to disperse the sludge into a miscible fraction, including JE1058BS, a new biosurfactant produced by Gordonia sp. strain JE-1058. Phylogenetic analysis of the 16SrRNA sequence of the strain JE-1058 identified Gordonia polyisoprenivorans. The sludge was efficiently removed by dispersion with biosurfactant at concentrations of 1-10 g/L, with stable dispersion at 10 g/L for 3 weeks. Addition of the BS caused no significant changes except for water content in the physicochemical factors such as density, viscosity, and sulfur/nitrogen content, suggesting that the novel biosurfactant JE1058BS is useful for oil tank bottom sludge treatment.
A new simple separation method was proposed for the laboratory-scale separation of asphaltene using columns packed with Teflon-beads. At first, a column packed with Teflon-beads having an inner diameter of 10-30 mm was washed with heptane, and then heavy oil–heptane solution was introduced into the column, followed by eluting remaining maltene using heptane. After the maltene recovery, dichloromethane was introduced from the bottom of the column to elute trapped asphaltene from the top of the column. The maximum asphaltene amount of the column under operational conditions was nearly proportional to the cross-section area of the column, for example, 0.8 g using a column having an inner diameter of 20 mm. The recoveries and H/C atomic ratio of maltenes and asphaltenes were almost the same as those obtained by conventional centrifugation methods, indicating the proposed method was equivalent to centrifugation methods. The proposed method was also useful for the recovery of small amounts of asphaltene such as 50 mg.