Kwang-Eun Jeong

Upgrading of biofuel by the catalytic deoxygenation of biomass

Biomass can be used to produce biofuels, such as bio-oil and bio-diesel, by a range of methods. Biofuels, however, have a high oxygen content, which deteriorates the biofuel quality. Therefore, the upgrading of biofuels via catalytic deoxygenation is necessary. This paper reviews the recent advances of the catalytic deoxygenation of biomass. Catalytic cracking of bio-oil is a promising method to enhance the quality of bio-oil. Microporous zeolites, mesoporous zeolites and metal oxide catalysts have been investigated for the catalytic cracking of biomass. On the other hand, it is important to develop methods to reduce catalyst coking and enhance the lifetime of the catalyst. In addition, an examination of the effects of the process parameters is very important for optimizing the composition of the product. The catalytic upgrading of triglycerides to hydrocarbon-based fuels is carried out in two ways. Hydrodeoxygenation (HDO) was introduced to remove oxygen atoms from the triglycerides in the form of H2O by hydrogenation. HDO produced hydrogenated biodiesel because the catalysts and process were based mainly on well-established technology, hydrodesulfurization. Many refineries and companies have attempted to develop and commercialize the HDO process. On the other hand, the consumption of huge amounts of hydrogen is a major problem hindering the wide-spread use of HDO process. To solve the hydrogen problem, deoxygenation with the minimum use of hydrogen was recently proposed. Precious metal-based catalysts showed reasonable activity for the deoxygenation of reagent-grade fatty acids with a batch-mode reaction. On the other hand, the continuous production of hydrocarbon in a fixed-bed showed that the initial catalytic activity decreases gradually due to coke deposition. The catalytic activity for deoxygenation needs to be maintained to achieve the widespread production of hydrocarbon-based fuels with a biological origin.

Catalytic upgrading of oil fractions separated from food waste leachate.

In this work, catalytic cracking of biomass waste oil fractions separated from food waste leachate was performed using microporous catalysts, such as HY, HZSM-5 and mesoporous Al-MCM-48. The experiments were carried out using pyrolysis gas chromatography/mass spectrometry (Py-GC/MS) to allow the direct analysis of the pyrolytic products. Most acidic components, especially oleic acid, contained in the food waste oil fractions were converted to valuable products, such as oxygenates, hydrocarbons and aromatics. High yields of hydrocarbons within the gasoline-range were obtained when microporous catalysts were used; whereas, the use of Al-MCM-48, which exhibits relatively weak acidity, resulted in high yields of oxygenated and diesel-range hydrocarbons. The HZSM-5 catalyst produced a higher amount of valuable mono aromatics due to its strong acidity and shape selectivity. Especially, the addition of gallium (Ga) to HZSM-5 significantly increased the aromatics content.

Tailor‐Made Mesoporous Ti‐SBA‐15 Catalysts for Oxidative Desulfurization of Refractory Aromatic Sulfur Compounds in Transport Fuel

We propose large‐pore titanium‐containing organosilylated mesoporous silica (Ti‐SBA‐15) as a highly efficient catalyst for the oxidative desulfurization (ODS) of refractory aromatic sulfur compounds with the aim to produce ultra‐low sulfur diesel. To achieve this, we synthesized a series of mesoporous Ti‐SBA‐15 catalysts according to a new procedure. The procedure is based on the controlled grafting of titanium chelates on SBA‐15 silica at low temperatures (5 °C). This specific synthesis procedure ensured a high dispersion of the required 4‐coordinate tetrahedral Ti4+ sites located on the mesopore surface. To substantiate the influence of the titanium content and mesopore size on the ODS performance of the catalysts, the parameters were varied in the range of 0.7 to 4.7 mol % (Si/Ti) and 5.1 to 9.0 nm, respectively. The resulting Ti‐SBA‐15 catalysts were then tested in the oxidative desulfurization (ODS) of model sulfur‐containing compounds in the presence of cumene hydroperoxide (CHP) as the organic oxidant. The ODS of a real industrial diesel fuel was also carried out in a continuous fixed bed reactor with the same Ti‐SBA‐15 catalysts and CHP. The catalytic results revealed that the Ti‐SBA‐15 catalysts with the largest pore sizes (>7.3 nm) and highest Ti contents (>2.8 mol %) were highly active catalysts for ODS reactions. Moreover, the catalysts with large pores and high Ti loadings appeared to be stable for over 30 h and were far less prone to deactivation than their equivalent Ti‐SBA‐15 samples with smaller pore diameters and lower Ti contents.

Catalytic production of hydrogen through aqueous-phase reforming over platinum/ordered mesoporous carbon catalysts

A series of platinum catalysts supported on ordered mesoporous carbon (CMK-3) with different Pt loadings from 1 to 10 wt% have been prepared, and their catalytic activities for hydrogen production viaaqueous-phase reforming (APR) of ethylene glycol (EG) have been investigated. Characterization by X-ray powder diffraction, transmission electron microscopy, N2 sorption, and CO chemisorption techniques reveal that an ordered mesostructure, high surface area, large pore volume, and uniform mesopore size in the mesopores are maintained with a high dispersion of platinum nanoparticles after APR of EG at 250 °C under 45 atm over 24 h. These results show that the structure of the ordered mesoporous carbon support exhibits outstanding hydrothermal stability in APR under high pressure and temperature. The APR activities of Pt/CMK-3 catalysts as a function of Pt loading were increased up to 7 wt% Pt loading. The optimum Pt loading was found to be 7 wt%, with a 37.8 cm3gcat−1 min−1hydrogen production rate. The results presented in this work suggest that Pt/CMK-3 is a very efficient catalyst for producing hydrogen in the APR reaction due to good hydrothermal stability with an open mesoporous structure. The findings presented here are expected to provide new opportunities for rational design of heterogeneous carbonaceous catalysts for aqueous-phase reactions under severe reaction conditions.

CrAPO-5 catalysts having a hierarchical pore structure for the selective oxidation of tetralin to 1-tetralone

A novel CrAPO-5 material having a unique microporous–mesoporous hierarchical pore structure (CrAPO-5H) was synthesized using an organosilane surfactant to conventional CrAPO-5 reaction mixture by a one-step hydrothermal process. The materials were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), N2-adsorption isotherm and UV-visible diffuse reflectance spectroscopy, and employed as a catalyst for the liquid phase oxidation of tetralin. CrAPO-5H produced higher activity than conventional microporous CrAPO-5. Acylperoxy radicals, in situ generated from trimethylacetaldehyde and O2, were more effective as oxidant than tert-butyl hydroperoxide (t-BuOOH); 88% conversion of tetralin with 97% selectivity to 1-tetralone was obtained with the former, whereas 57% conversion with 86% selectivity was achieved using the latter at 80 °C after 8 h. The effect of reaction temperature, Cr content, solvent, and the type of aldehyde employed for the in situ generation of acylperoxy radicals on catalytic performance was investigated. Activities of CrAPO-5H remained constant after 1st catalyst recycle. A hot filtration experiment coupled with a blank test revealed that oxidation proceeded mostly on Cr sites in the CrAPO-5H, but a minor contribution from trace amount of leached Cr could not be ruled out.

Synthesis of a sulfonato-salen-nickel(II) complex immobilized in LDH for tetralin oxidation

A novel sulfonato-salen-nickel(II) complex has been immobilized on a Zn(II)-Al(III) layered double hydroxide (LDH) host. XRD, FT-IR, TGA and UV-vis spectroscopy, as well as chemical analysis, confirmed the successful incorporation of the nickel-salen complex within the LDH structure. BET surface area measurements, SEM and TEM were also used to characterize the heterogenized catalyst. The sulfonato-salen-nickel(II) complex-immobilized material, LDH-[nickel-salen], was found to be effective in the oxidation of tetralin, where a combination of trimethylacetaldehyde and dioxygen at atmospheric pressure was employed as the oxidant. At 72.3% conversion, tetralin was converted to 1-tetralone with 72.2% selectivity at 70 °C after 7 h. Tetralin oxidation using tert-butyl hydroperoxide afforded a lower conversion and selectivity of 1-tetralone than with trimethylacetaldehyde and dioxygen as the oxidant. The effect of various reaction parameters on catalytic performance was also investigated. A hot filtration experiment coupled with a blank test revealed that oxidation proceeded mostly on nickel-salen sites in LDH-[nickel-salen]. A reaction mechanism is proposed based on the experimental results.

Selective synthesis of C3–C4 hydrocarbons through carbon dioxide hydrogenation on hybrid catalysts composed of a methanol synthesis catalyst and SAPO

Abstract Direct synthesis of hydrocarbons through carbon dioxide hydrogenation was investigated over hybrid catalysts composed of methanol synthesis catalysts (Cu/ZnO/ZrO 2 and Cu/ZnO/Al 2 O 3 ) and molecular sieves (H-ZSM-5, SAPO-5 and SAPO-44). It was found that the hybrid catalyst with SAPO-5 or SAPO-44 was effective for the synthesis of C 2+ hydrocarbons. The high hydrocarbon yield appears to be due to the abundance of weak- and medium-strength acid sites in SAPO, which could be evidenced through temperature-programmed desorption of ammonia. The product distribution of hydrocarbon products was influenced by the acidity as well as the pore size of the molecular sieves. The selectivity to isobutane was the highest on the hybrid catalysts with SAPO-5. Propane was the main product on the hybrid catalyst with SAPO-44. Carbon dioxide conversion increased with reaction temperature, but a maximum yield of C 2+ hydrocarbon was obtained at 340°C. An increase in contact time lowered the carbon monoxide formation and increased the hydrocarbon formation. Addition of carbon monoxide or ethene to the feed increased the hydrocarbon yield. The reaction pathway to hydrocarbons is thought to be composed of methanol synthesis from carbon dioxide and hydrogen, methanol/dimethyl ether to lower alkene, alkene oligomerization, isomerization and hydrogenation to alkane.

Production of Biohydrogen by Aqueous Phase Reforming of Polyols over Platinum Catalysts Supported on Three‐Dimensionally Bimodal Mesoporous Carbon

Now in 3D! Three-dimensionally bimodal carbons (3D-BMC) with mesopores of tunable size (controlled through the polymerization of the carbon precursor) are synthesized. After loading with platinum, the catalysts are used in aqueous phase reforming of polyols, and show superior performance in terms of carbon conversion, hydrogen yield, selectivity, and hydrogen production rate compared to platinum catalysts supported on activated carbon or two-dimensional CMK-3.

Selective oxidation of refractory sulfur compounds for the production of low sulfur transportation fuel

The current technologies for achieving low sulfur in diesel fuel are based on hydrotreating, which requires high temperature, high pressure and excessive supply of hydrogen. Oxidative desulfurization (ODS) is considered one of the promising new methods for super deep desulfurization, which could be carried out under very mild conditions (atmospheric pressure, <100 °C) without consumption of hydrogen. In this paper, development status of ODS process by major licensors are described as well as general concepts of ODS reaction. In addition, the ODS process has been categorized into single phasic and biphasic system according to the oxidants involved. Recent trends in both systems are reviewed in detail and future work is also proposed.

Catalytic pyrolysis of Laminaria japonica over nanoporous catalysts using Py-GC/MS

The catalytic pyrolysis of Laminaria japonica was carried out over a hierarchical meso-MFI zeolite (Meso-MFI) and nanoporous Al-MCM-48 using pyrolysis gas chromatography/mass spectrometry (Py-GC/MS). The effect of the catalyst type on the product distribution and chemical composition of the bio-oil was examined using Py-GC/MS. The Meso-MFI exhibited a higher activity in deoxygenation and aromatization during the catalytic pyrolysis of L. japonica. Meanwhile, the catalytic activity of Al-MCM-48 was lower than that of Meso-MFI due to its weak acidity.