Conversion of Multicyclic Hydrocarbons to Mono-Aromatic Hydrocarbons Over CoMo/Zeolite Socony Mobil-5 Catalysts.

This study focuses on analyzing the effects of the SiO2/Al2O3 ratio of a support on the physico-chemical properties of bead-type CoMo/HZSM-5 catalysts and on the catalytic performance during the hydrocracking reaction of PFO. CoMo/HZSM-5 catalysts were prepared by an incipient wetness method. Subsequently, binder-added catalysts were molded into the bead type catalysts. The N2 adsorption-dersorption results clearly indicate that the nanoporous structure was well developed in the bead-type CoMo/HZSM-5 catalyst. The CoMo/HZSM-5(30) catalyst not only possessed the highest number of acid sites but also showed the highest ratio of strong acid to weak acid sites. Moreover, the Lewis acid/Brönsted acid site ratio is highest with the CoMo/HZSM-5(30) catalysts. A hydrocracking reaction of PFO over the bead-type CoMo/HZSM-5 catalysts was conducted at 400 °C and under 40 atm in a fixed-bed reactor. The bead-type CoMo/HZSM-5(30) catalyst showed the highest BTXE yield with a sum of BTXE outcome of 43.0% in the catalytic cracking reaction of PFO, which is attributed to the synergistic combination of suitable acidity and hierarchical porosity.

Isotherm, Kinetic and Thermodynamic Studies on Adsorption of Bromocresol Purple, Acid Red 66 and Acid Blue 40 Using Activated Carbon.

This study was conducted with a batch reaction to equilibrium isotherm, kinetic and thermodynamic parameters on adsorption of bromocresol purple (BCP), acid red 66 (AR 66) and acid blue 40 (AB 40) from aqueous solution by using activated carbon with nanopores. Freundlich and Temkin isotherm models were used to evaluate the suitability of isotherm for adsorption equilibrium data. The adsorption equilibrium was best fitted by Temkin model. The Freundlich separation factor values indicated that adsorption on the nanoporous activated carbon could effectively treat three dyes. The kinetic analysis of the adsorption process confirmed that it was more consistent with the pseudo second order model. The intraparticle diffusion was rate limiting step. The adsorption process of three dyes were endothermic because they were positive enthalpy values. The free energy values of three dyes decreased with increasing temperature, so that the spontaneity becomes higher with temperature increase. The activation energy value of three dyes were confirmed the physical adsorption.

Hydrogenation of Ethylbenzene Over Ru/γ-Al2O3 Catalyst in Trickle-Bed Reactor.

The objective of this study is to evaluate the catalytic performance of pellet-type Ru/γ-Al2O3 as a catalyst during liquid-phase hydrogenation of the aromatic hydrocarbon. The Ru/γ-Al2O3 catalyst was prepared using a wet impregnation method. After adding a binder to Ru/γ-Al2O3, a pellet-type catalyst was obtained through an extrusion method. Nanoporous structures are well developed in the pellet-type Ru/γ-Al2O3 catalyst. The average pore sizes of the Ru/γ-Al2O3 catalysts were approximately 10 nm. The catalytic performance of the pellet-type Ru/γ-Al2O3 catalyst during ethylbenzene hydrogenation was evaluated in a trickle-bed reactor. When the ruthenium loading increased from 1 to 5 wt%, the number of active sites effective for the hydrogenation of ethylbenzene increased proportionally. In order to maximize the conversion of ethylbenzene to ethylcyclohexane, it was necessary to maintain a liquid phase hydrogenation reaction in the trickle bed reactor. In this regards, the reaction temperature should be lower than 90 °C. The conversion of ethylbenzene to ethylcyclohexane on the Ru(5 wt%)/γ-Al2O3 catalyst was highest, which is ascribed to the largest number of active sites of the catalyst.

The Use of Low Cost Nanoporous Catalysts on the Catalytic Pyrolysis of Polyethylene Terephthalate.

This study evaluated the feasibility of low-cost nanoporous catalysts, such as dolomite and red mud, on the production of aromatic hydrocarbons via the catalytic pyrolysis of polyethylene terephthalate (PET). Compared to the non-catalytic pyrolysis of PET, catalytic pyrolysis over both dolomite and red mud produced larger amounts of aromatic hydrocarbons owing to their catalytic cracking efficiency and decarboxylation efficiency. Between the two catalysts, red mud, having a larger BET surface area and higher basicity than dolomite, showed higher efficiency for the production of aromatic hydrocarbons.

Improved Performance of High Energy Materials Based on Dinitramide Salts and Its Liquid Monopropellant.

As an eco-friendly alternative fuel material, ammonium dinitramide (ADN, NH4N(NO2)2) is safe and stable at room temperature; however, it requires high purity for practical applications. A small amount of impurities can retard the catalytic decomposition of the monopropellant in the thruster, lower the specific impulse, and induce side effects such as clogging of the nozzle. Therefore, we purified NH4N(NO2)2 by performing repeated extractions, adsorption by powdered activated carbon, and low-temperature extractions. In this study, we evaluated the chemical density of purified NH4N(NO2)2 through Fourier-transform infrared spectroscopy, ultraviolet-visible spectroscopy, and ion chromatography, and obtained a final purity of 99.8%. Furthermore, we fabricated a liquid fuel using high-purity NH4N(NO2)2 as the main oxidizing agent, and can be prepared a mono-propellant formulation that exhibited decomposition at a minimum temperature of 148 °C.

Decomposition of Hydroxylammonium Nitrate Solution Over Nanoporous CuO Supported on Honeycomb.

We investigated the influence of a copper loading strategy over a honeycomb structure on the catalytic performance during the decomposition of a hydroxylammonium nitrate (HAN) aqueous solution. Copper was supported on the honeycomb surface by means of a metal coating method (MC), i.e., a method of directly coating a metal, and a metal alumina coating method (MAC), i.e., a method of coating a mixture of metal and alumina. The properties of the catalysts were analyzed by N2 adsorption, X-ray diffraction (XRD), and scanning electron microscopy (SEM). The Cu(16.8)/honeycomb-MC catalyst showed a lower decomposition onset temperature during the decomposition of the HAN aqueous solution compared to that over the Cu(7.0)/honeycomb- MAC catalyst, an outcome ascribed to the higher copper loading and the higher dispersion of copper in the Cu(16.8)/honeycomb-MC catalyst compared to that in the other catalyst. The Cu(16.8)/honeycomb-MC catalyst was confirmed to have both excellent activity and heat resistance during the decomposition of a HAN aqueous solution.

Effect of zeolite acidity and structure on ozone oxidation of toluene using Ru-Mn loaded zeolites at ambient temperature.

Five different Ru-Mn/zeolites were used to investigate their catalytic efficiencies for removing toluene (100 ppm) with ozone (1000 ppm) at room temperature. In general, most of metal oxide catalysts for removal of organic compounds need higher temperature than the ambient temperature, but Mn-based catalysts shows activity for prevalent organic pollutants even at room temperature with ozone. For the removal of toluene at room temperature without further heating, bimetallic Ru added Mn catalysts were applied in combination with different zeolite supports. The catalytic activity of the Ru-Mn catalysts strongly depended on the zeolite, of which the characteristics such as acidity and adsorption degree of toluene are dependent on the ratio of SiO2/Al2O3. Among the five Ru-Mn catalysts used, Ru-Mn/HY (SiO2/Al2O3 ratio: 80) and Ru-Mn/ZSM-5 (SiO2/Al2O3 ratio: 80) had higher toluene and ozone removal efficiencies. The toluene removal efficiency of Ru-Mn/zeolites was proportional to the pore volume and surface area. In terms of ozone degradation, Ru-Mn/HY(80) and Ru-Mn/HZSM-5(80) had the highest removal efficiencies. Overall, the catalytic ozone oxidation of toluene using Ru-Mn/zeolites seemed to be affected by a combination of the acidic properties of zeolites, Mn3+/Mn4+ ratio, and concentration ratio of oxygen vacancies to oxygen lattices on the catalyst surface.

Biohydrogen production from catalytic conversion of food waste via steam and air gasification using eggshell- and homo-type Ni/Al2O3 catalysts.

Steam and air gasification with 5 wt% Ni/Al2O3 eggshell (Ni-EG) and homo (Ni-H) catalysts were performed for the first time to produce biohydrogen from food waste. The steam gasification produced comparably higher gas yield than air gasification. In non-catalytic experiments, steam gasification generated a higher volume percent of H2, whereas more CO, CO2, CH4, and C2-C4 were produced in air gasification. Ni-EG demonstrated higher potential to obtain H2-rich gases with a low C2-C4 content compared to that obtained by Ni-H, particularly in steam gasification at 800 °C, which produced gaseous products with 59.48 vol% H2. The long-term activity of both catalysts in steam gasification was evaluated, and Ni-EG exhibited higher stability than Ni-H. The ideal distribution of Ni species on the outer region of γ-Al2O3 pellets in Ni-EG resulted in higher activity, stability, and selectivity than Ni-H in both steam and air gasification.

Synthesis Optimization of Guanidinium Dinitramide (GDN).

Dinitramide anion [-N(NO2)2] salt composed of resonance structure is a plausible oxidizing agents, as efficient propellant. Among them, guanidinium dinitramide (GDN) is an organic compound improving the stability against moisture, as well long term storage. An additional advantage composed guanidinium ion is the reaction efficient via the decomposed by-product during pyrognostics, maximum yield of 99%. The types of GDN (GDN-I, II, III, IV, V) were synthesized using several starting material such as guanidine acetate, chloride, carbonate, nitrate and sulfate under hydrodeprivation. In this work, the intermediates formed in these processes were closely identified and their thermal properties, and chemical structure were examined. The absorption peaks by Fourier transform infrared (FT-IR) were found guanidinium infrared frequencies (3452, 3402, 3354, 3278, 1642 cm-1) and dinitramide infrared frequencies (3208, 1570, 1492, 1416, 1337, 1179, 1000 cm-1). The activation energy of GDN samples were obtained Ea = 53.26 Kcal/mole (GDN-I), 50.94 Kcal/mole (GDN-II), 52.34 Kcal/mole (GDN-III), 62.19 Kcal/mole (GDN-IV), 55.32 Kcal/mole (GDN-V) from exothermic at over 153°C.

Decomposition of Energetic Ionic Liquid Over IrCu/Honeycomb Catalysts.

The objective of this study is to elucidate the influence of a loading procedure of iridium and copper oxides over cordierite honeycomb support on catalytic performance during the decomposition of a hydroxylammonium nitrate (HAN) solution. Iridium and copper composite oxides were successfully supported on the cordierite honeycomb at the same time by repeating the wash coating process more than 2 times. Through the wash coating process, Cu and Ir were supported up to 43.4% and 4.9%, respectively. The cordierite honeycomb without active metal plays little role as a catalyst to lower the decomposition temperature. It was found that IrCu/honeycomb-2 catalyst, which was prepared by repeating the wash coating procedure twice, is an optimal catalyst for the decomposition of HAN solution. The IrCu/honeycomb-2 catalyst had the effect of lowering the decomposition onset temperature by 27.1°C compared to thermal decomposition.

Catalytic Decomposition of Energetic Liquid Solution Over Various Types of Hexaaluminate Catalysts.

A hexaaluminate support was prepared by a co-precipitation method, and a metal (Cu, Pt, or Ir) was impregnated on the support to prepare a powdered catalyst. After that, organic and inorganic binders were added to the powdery catalyst and then pellets were formed. The so-formed catalysts were heat-treated at 1200°C, and their physicochemical properties were analyzed by N2-adsorption, X-ray diffraction (XRD), X-ray fluorenscence (XRF), and scanning electron microscopy (SEM). The decomposition activity of the catalysts on an ammonium dinitramide (ADN)-based liquid propellant was evaluated repeatedly, and the effects of catalyst composition and morphology on low temperature decomposition activity and durability were investigated. It was confirmed that the Cu-hexa-pellet, Pt-hexa-pellet, and Ir-hexa-pellet catalysts could be recovered and reused as a catalyst for decomposition of an ADN-based liquid monopropellant. The initial activity and the thermal stability of the Cu-hexa-pellet catalyst for the decomposition of ADN-based liquid monopropellants were better than for the other catalysts. The better activity of the Cu-hexa-pellet catalyst seems to be because the dispersion of the copper was higher than the metal dispersion in the other two catalysts.

Catalytic ozonation of toluene using Mn-M bimetallic HZSM-5 (M: Fe, Cu, Ru, Ag) catalysts at room temperature.

We investigated the catalytic efficiency of Mn-based bimetallic oxides in degrading toluene and ozone at room temperature. The room temperature-active bimetallic oxide catalysts were prepared by the addition of Fe, Cu, Ru, and Ag precursors to Mn/HZSM-5. We obtained H2-temperature-programmed reduction (H2-TPR) profiles, X-ray diffraction patterns, and X-ray photoelectron spectra to investigate the characteristics of the prepared catalysts. The catalytic efficiency of Mn-based bimetallic oxide catalysts in degrading toluene and ozone at room temperature was mostly improved by the addition of the secondary metals. The prepared bimetallic oxide catalysts, Cu-Mn/HZSM-5, Fe-Mn/HZSM-5, Ru-Mn/HZSM-5, and Ag-Mn/HZSM-5, enhanced efficiency for toluene removal compared to Mn/HZSM-5. The H2-TPR profiles of the Mn-based bimetallic oxide catalysts showed stronger and broader adsorption-desorption bands at lower temperatures than the profile of Mn/HZSM-5. Additionally, the ratio of the surface defective oxygen over the lattice oxygen on the bimetallic oxide catalysts was higher than that of Mn-only catalysts; the ratio of Mn3+ over Mn4+ was higher for all bimetallic oxide catalysts, as well. Among the bimetallic oxide catalysts, Ru-Mn/HZSM-5 showed the highest efficiency for the removal of toluene to COx due to the synergetic effect of the oxidation state and reducible potential at room temperature.

Performance of Pt and Ir Supported on Mesoporous Materials for Decomposition of Hydroxylammonium Nitrate Solution.

The catalytic decomposition of hydroxylammonium nitrate (HAN) was investigated using a series of platinum and iridium supported on mesoporous materials. In this study, MMZY, KIT-6, and SBA-15 were used as supports. The effects of the active metal and the pore structure of the catalysts on decomposition of HAN solution were studied. The activity of the platinum catalysts supported on mesoporous material is much superior to that of the iridium catalysts on the same support. The Pt(10)/SBA-15 catalyst showed excellent decomposition activity and was the best among the catalysts tested here, which seemed to be because of the pore structure of Pt(10)/SBA-15. Because the pore size of Pt(10)/SBA-15 is larger than that of Pt(10)/MMZY and Pt(10)/KIT-6, it is more advantageous for diffusion of reactant and product gas. The activity of the catalyst increased as the amount of Pt loaded on the SBA-15 support increased.

Decomposition of Ionic Liquid Solution Over CuIr-Hexaaluminate Catalysts.

The objective of this study is to elucidate the catalytic performance of hexaaluminate catalysts incorporating Cu and Ir simultaneously during the decomposition of an ammonium dinitramide (ADN)-based liquid propellant. Pellet-type catalysts were prepared and their chemico-physical properties were characterized by N2 adsorption, XRD, and XRF. It was confirmed that Cu and Ir atoms are well incorporated inside the hexaaluminate matrix of the Cu(x)Ir(10-x)-hexaaluminate catalysts and the content of Ir incorporated into hexaaluminte matrix was in the range of 2.5-8.2 wt%. The Cu(7)Ir(3)-hexaaluminate catalyst showed excellent activity in decomposition of ADN-based liquid monopropellant. The activity of the Cu(7)Ir(3)-hexaaluminate catalyst was much higher than that of the Cu(7)Ir(3)/hexaaluminate-imp catalyst prepared by impregnation of Cu and Ir onto the hexaaluminate pellet surface. This is attributed to the Cu and Ir being well incorporated in the hexaaluminate matrix and the dispersion of the Cu and Ir being greater in the Cu(7)Ir(3)-hexaaluminate than in the Cu(7)Ir(3)/hexaaluminate-imp.

Catalytic Decomposition of an Ionic Liquid Monopropellant Over Ir/Hexaaluminate Catalysts.

The aim of this study is to elucidate the influence of an iridium loading strategy over hexaaluminate on the catalytic performance during the decomposition of liquid monopropellants based on ammonium dinitramide (ADN). Powder-type and pellet-type Ir/hexaaluminate catalysts were prepared and their chemico-physical properties were characterized by N2 adsorption, XRD, XRF, and SEM. There were considerable differences in the Ir amounts present on the surface according to the impregnation method employed. The catalytic activities of three types of Ir/hexaaluminate catalysts to decompose the ADN-based liquid monopropellant were compared using a semi-batch type of reactor. Pellet-type Ir/hexaaluminate catalyst, which formed hexaaluminate into a pellet and where iridium was impregnated during the last stage, showed the lowest onset temperature during the decomposition of the ADN-based liquid monopropellant, having the effect of lowering the decomposition onset temperature by around 60 °C compared to that without a catalyst. This was due to the pellet-type Ir/hexaaluminate having a larger surface area and a large number of Ir active sites on its surface.

Hydrogenation of Tricyclopentadiene Over Ru Supported on Ordered Nanoporous Silica.

Tetrahydrotricyclopentadine (THTCPD) has been used as a fuel with a high energy density. THTCPD is produced by the hydrogenation of tricyclopentadiene (TCPD). In this study, Ru/nanoporous silica catalysts are utilized as a catalyst for TCPD hydrogenation. Ru/KIT-6 and Ru/SBA-15 show significantly higher activity compared to outcomes over the Ru/kieselguhr catalyst during TCPD hydrogenation. The nanoporous structures of Ru/KIT-6 and Ru/SBA-15 help to overcome the diffusion limitations of reactants and products during the TCPD hydrogenation process. In addition to the diffusion factors, the distribution of Ru crystallites on the support plays an important role in the TCPD hydrogenation activity.

Effects of Zeolite Supports on the Production of Fuel-Range Hydrocarbons in the Hydrotreatment of Various Vegetable Oils with Platinum-Based Catalysts.

The effects of catalyst supports on catalyst performance in the hydrotreatment of vegetable oils (to produce fuel-range hydrocarbons such as gasoline, jet fuel, and diesel) were investigated, using three types of zeolites (ZSM-5, HY, and zeolite-beta (BEA)) that differ in their silica/alumina ratios. Structural characterization of the catalysts was performed using ICP, XRD, BET, TEM, and NH3-TPD. Catalytic tests were carried out in a fixed-bed reaction system at 400 °C and 50 bar. In the hydrotreatment of soybean oil, higher conversions into liquid hydrocarbons and fuel-range hydrocarbons were found when supports with lower Si/Al2 ratios were used. Specifically, Pt/BEA (Si/Al2 = 25) produced the highest conversion into liquid products (72%) and the highest selectivity for hydrocarbons in the jet fuel (46%) and diesel (51%) fuels. A Pt loading amount of 3 wt% in this catalyst gave the best catalytic performance because of the optimal balance between acidic and metallic sites. Finally, the kinds of vegetable oils in the hydrotreatment performance over Pt/BEA (Si/Al2 = 25) affected the order; waste-cooking oil > jatropha oil > soybean oil.

Hydroupgrading of Bio-Oil Over PtMg/KIT-6 Catalysts.

The objective of this study is to evaluate the catalytic potential of PtMg/Al-KIT-6 during the hydroupgrading of a mixture composed of C15-C18 alkane as a model compound of bio-oil obtained by a hydrodeoxygenation of palm oil. Al-KIT-6 was prepared through a post-alumination method using KIT-6, after which platinum and magnesium precursors were impregnated onto the synthesized Al-KIT-6. PtMg/Al-KIT-6 catalysts were shown to have a well-arranged mesoporous structure, a large surface area, and a large pore size. The jet-fuel yield (55-59%) in the hydroupgrading of the long-chain n-alkane mixture over PtMg/Al-KIT-6 catalysts was much higher than that over the PtMg/KIT-6 catalyst, which could be ascribed to the higher number of acid sites of the PtMg/Al-KIT-6 catalysts. The highest isomer selectivity of the PtMg/Al-KIT-6(20) catalyst can be attributed to the strong acidity as well as the abundance of acid sites. PtMg/Al-KIT-6 catalysts can be effective catalysts for producing jet fuel through the hydroupgrading of bio-oil.

Ordered Mesoporous Cu-Mn Metal Oxides for the Catalytic Decomposition of an Energetic Ionic Liquid.

Ordered mesoporous Cu-Mn binary metal oxide (meso-CuMnOx) catalysts were successfully synthesized by a hard-templating method from a mesoporous silica template with a cubic Ia3d mesostructure (KIT-6) or hydrophobic KIT-6, exhibiting a well-developed crystalline framework, a regular pore size distribution and a high surface area. The copper and manganese elements in the mesoporous Cu-Mn binary metal oxides (meso-CuMnOx-N and meso-CuMnOx-HP), obtained from the KIT-6 and hydrophobic KIT-6, respectively, were homogeneously dispersed in the whole particles. The activities of meso-CuMnOx catalysts for the decomposition of a liquid monopropellant containing an energetic ionic liquid, ammonium dinitramide, were much higher than that over a CuMnOx catalyst prepared by a conventional precipitation method. This is attributed to the well-developed mesoporosity of the meso-CuMnOx catalysts. Among the mesoporous CuMnOx catalysts, the decomposition onset temperature over meso-CuMnOx-HP (87.9 °C) was found to be lower than that over meso-CuMnOx-N (100.4 °C), probably due to its higher mesoporosity and surface area.

Catalytic Pyrolysis of Organosolv and Klason Lignin Over Al-SBA-15.

The catalytic pyrolysis of two types of lignin, organosolv and klason lignin, which were extracted from miscanthus, over Al-SBA-15 was carried out using a thermogravimetric (TG) analyzer and a pyroyzer-gas chromatography/mass spectrometry (Py-GC/MS). Although Al-SBA-15 has weak acidity, the large molecular phenolic pyrolyzates of lignin were converted effectively into small molecular phenols and aromatic hydrocarbons due to the large pore size of Al-SBA-15. Compared to klason lignin, organosolv lignin produced larger amounts of valuable chemicals, such as mono-phenol, mono-aromatics, and furans, by catalytic pyrolysis over Al-SBA-15.