Ho-Jeong Chae

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.

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.

Hydrogenation of carbon monoxide to higher alcohols over ordered mesoporous carbon nanoparticle-supported Rh-based catalysts

Abstract Two-dimensional hexagonally ordered mesoporous carbon nanoparticles (MCNs) were synthesized using the templating synthesis method. MCNs were introduced as supports for the catalytic thermochemical conversion of syngas to higher alcohols. The catalytic test of the promoted Rh/MCNs was performed using a fixed bed reactor. The catalytic results reveal that the nano-sized MCN-supported catalysts exhibited higher C2+ alcohol production with a high ethanol selectivity compared with the micro-sized ordered mesoporous carbon-supported catalysts. The promoted Rh/CMK-5-MCN with a hollow framework configuration exhibited a superior space–time yield of the total C2+ alcohols compared with the promoted Rh/CMK-3-MCN with a rod carbon framework. It indicates that the promoted Rh/MCNs exhibited different catalytic activities and selectivities of higher alcohols, which is attributed to the Rh particle size and the reactant accessibility to active sites through the morphological effects of the MCNs.

The Role of Ruthenium on Carbon-Supported PtRu Catalysts for Electrocatalytic Glycerol Oxidation under Acidic Conditions

A series of binary PtRu catalysts with different Pt/Ru atomic ratios (from 7:3 to 3:7) were synthesized on a carbon support using the colloidal method; they were then used for electrooxidation of glycerol in acid media. X‐ray diffraction, transmission electron microscopy, X‐ray photoelectron spectroscopy, and X‐ray absorption spectroscopy analyses were used to investigate particle size, size distribution, and structural and electronic properties of the prepared catalysts. Ru added to the Pt‐based catalysts caused structural and electronic modifications over the PtRu alloy catalyst formation. The electrocatalytic activities of PtRu/C series catalysts were investigated using cyclic voltammetry. The Pt5Ru5/C catalyst shows enhanced catalytic activity at least 40 % higher than that of the Pt/C catalyst, with improved stability for glycerol electrooxidation; these improvements are attributed to structural and electronic modifications of the Pt catalysts. Using an electrocatalytic batch reactor, product analysis after the oxidation reaction was performed by high‐performance liquid chromatography to determine and compare the reaction pathways on the Pt/C and PtRu/C catalysts. To understand different catalytic activities of glycerol oxidation on the PtRu alloy surfaces, density functional calculations were performed.

Comparative study of CHA- and AEI-type zeolytic catalysts for the conversion of chloromethane into light olefins

Three pairs of CHA- and AEI-type zeolytic materials with similar crystallite size but with different framework atoms, i.e., silicoaluminophosphate SAPO-34 and SAPO-18, aluminosilicate SSZ-13 and SSZ-39, and titaniumin-corporated TiAPSO-34 and TiAPO-18, were prepared and their catalytic activities of chloromethane into light olefins were compared according to the structure types, as well as acidic properties. The AEI-type catalysts were found to have lower ethene/propene ratios, indicating relatively higher propene selectivity, because their aei-cage was larger compared to the cha-cage. However, all the CHA-type catalysts exhibited better activity and higher selectivity to light olefins. Both H-SAPO-34 and H-TiAPSO-34 showed good catalytic stability over all the reaction times studied here. When compared to H-SAPO-34, however, H-TiAPSO-34 exhibited ca. 20mol% higher selectivity to ethene and propene, despite a similar total density of acid site. This performance may be due to the higher strength of medium acid sites.