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This study examined the role of the support material on the coupling of 1,4-butanediol (BDO) dehydrogenation and nitrobenzene (NB) hydrogenation over copper-based catalysts. The catalysts, 10Cu/MgO (10CM), 10Cu/Al2O3 (10CA), 10Cu/MgO-Al2O3 (10CMA), and 10Cu/SiO2 (10CS), were prepared using the impregnation method. The coupling reaction results conducted at 250 °C were compared with those of the individual reactions. The individual BDO dehydrogenation to γ-butyrolactone (GBL) conversion (99%) and hydrogenation of NB to aniline (AN) conversion (85 %) were high over 10CS. In contrast, 10CA produced tetrahydrofuran (THF) as a major product from BDO. Interestingly, the coupling process over the 10CM catalyst produced the best performance in converting NB (65%) to AN (99%) and BDO (85%) to GBL (99%). The superior performance of Cu/MgO in coupling process catalyst is mainly due to the high hydrogen adsorption ability compared to the other catalysts under limited hydrogen environments, which helps retain the active hydrogen on the catalyst surface for a longer time. The characterization of the catalysts showed that a high basic nature and the optimal amount of active copper sites (Cu0/Cu1+) are responsible for the best performance of 10CM, followed by 10CS and 10CMA.

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.

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.

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.

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.

This study adapted two types of heterogeneous catalysts to the process of manufacturing biodiesel through a two-stage process using Jatropha oil as a raw material. The acid value of Jatropha oil prepared in this study was 11.3 mgKOH/g, and it could be reduced to less than 0.4 mgKOH/g via 2 h of esterification using the Amberlyst-15 catalyst. The pretreated oil was used as a raw material for transesterification in a Carberry spinning catalyst basket reactor equipped with a bead-type dolomite catalyst, as the bead-type dolomite catalyst prepared with 20 wt% pseudoboehmite sol as an inorganic binder was found to be the optimal catalyst for the transesterification reaction. The spent dolomite bead catalyst could be regenerated and reused twice without a loss of activity during transesterification. However, the catalyst when repeatedly regenerated three times nearly lost its active sites, which is attributed to the conversion of CaO to CaCO3 during the regeneration and reuse procedure.

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.

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.

The objective of this study is to elucidate the effects of MgO promotors on the catalytic physico-chemical properties of Ru/γ-Al2O3 catalysts and the activity during the tricyclopentadiene (TCPD) hydrogenation reaction. Ru/γ-Al2O3 and Ru-MgO/γ-Al2O3 catalysts were produced by means of a coprecipitation method and formed in a bead type. The specific surface area of the regenerated Ru-MgO/γ-Al2O3 catalyst is much larger than that of the regenerated Ru/γ-Al2O3 catalyst. It was confirmed that the addition of MgO has the effect of alleviating the decrease of the specific surface area during the repetitive regeneration procedure. The addition of MgO had no significant effect on the reducibility of the Ru/γ-Al2O3 catalyst. The results of XRD, CO chemisorption and TEM imagery show that the addition of MgO to the Ru/γ-Al2O3 catalyst has the effect of decreasing the mobility of Ru atoms during repetitive regeneration at 650 °C. It was confirmed that the degree of catalyst deactivation during four repetitive regeneration trials was much lower than that with an unpromoted catalyst, likely because the addition of MgO prevented the sintering of Ru at the regeneration temperature of 650 °C. The Ru-MgO/γ-Al2O3 catalyst is a possible candidate as a reusable catalyst for use during the TCPD hydrogenation reaction.

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.

Hierarchical zeolites have superior catalytic properties over purely microporous zeolites, leading to the enhanced diffusivity of molecules and strong acidity of the catalyst. In this study, hierarchical desilicated mesoporous ZSM-5 and Beta were prepared by the desilication of commercial microporous zeolites and applied to the catalytic pyrolysis of wood polymer composites. Hierarchical desilicated mesoporous ZSM-5 and Beta showed the typical X-ray diffraction patterns of microporous ZSM-5 and Beta with higher mesoporosity compared to the parent materials. The activity of the desilicated zeolites for the catalytic pyrolysis of wood polymer composites was evaluated using a thermogravimetric analysis and tandem micro reactor-gas chromatography/mass spectrometry. Among the catalysts tested, the lowest decomposition temperatures of wood polymer composites were observed using hierarchical desilicated mesoporous Beta followed by hierarchical desilicated mesoporous ZSM-5 and ZSM-5. This trend correlated well with the mesoporosity of the catalysts. The formation efficiency of hierarchical desilicated mesoporous ZSM-5 was highest followed by microporous ZSM-5, hierarchical desilicated mesoporous Beta, and Beta, indicating that in addition to mesoporosity, the shape selectivity induced by microporosity and strong acidity are important for the aromatization of pyrolysis vapors. In addition, the aromatic formation efficiency of the catalysts differed according to the properties of wood polymer composites. Compared to wood polymer composite 2, wood polymer composite 1 produced a larger quantity of aromatics during catalytic pyrolysis over all the catalysts at 500 °C owing to its higher polyethylene content. Both wood polymer composites exhibited a similar aromatic formation efficiency during catalytic pyrolysis at 600 °C because the diffusion hindering effect of polypropylene molecules to the catalyst pores was lower at the higher temperature.

We investigated the influence of a copper loading strategy over hexaaluminate on catalytic performance during the decomposition of an ammonium dinitramide (ADN)-based liquid propellant. Powder-type and pellet-type Cu/hexaaluminate catalysts were prepared and their chemico-physical properties were characterized by N2 adsorption, XRD, and XRF. A Cu-hexa-pellet-A catalyst in which copper atoms are positioned inside the hexaaluminate matrix showed the lowest decomposition onset temperature in decomposition of an ADN-based propellant The excellent activity of the Cu-hexa-pellet-A catalyst is ascribed to copper being well incorporated in the hexaaluminate matrix, and the dispersion of the copper is higher than that in two other catalysts. When a thermal shock was applied at a high temperature of 1,200 °C prior to catalyst reuse, physical properties such as surface area, average pore diameter, and the compressive strength of the fresh catalyst did not deteriorate remarkably after five times repetitive reuse and heat treatment. Consequently, the Cu-hexa-pellet-A catalyst was confirmed to be a catalyst that has excellent activity and heat resistance simultaneously in decomposition of an ADN-based propellant.

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.

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.

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.

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.

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.

A highly ordered mesoporous aluminosilicate (MMZY) was prepared by a top-down and bottom-up method using HY zeolite as a raw material. A pellet-type catalyst was prepared through extrusion using a twin-screw extruder. The effects of the Si/Al2 ratio of the HY zeolite used in the MMZY catalyst preparation on the physicochemical and acid properties of MMZY catalysts were investigated. The oligomerization of endo-dicyclopentadiene (endo-DCPD) was performed in a spinning basket reactor, and the deactivated catalyst was repeatedly regenerated to verify the possibility of reusing the catalyst. It was confirmed that ordered hexagonal arrays of mesopores were well developed in the MMZY(27) and MMZY(48) catalysts, whereas the mesoporous structure of the MMZY(6) and MMZY(12) materials with relatively large amounts of Al collapsed. As the Si/Al2 molar ratio of the MMZY catalyst was increased, the number of weak acid sites increased prominently and the acid strength decreased. MMZY(27) and MMZY(48) are more effective for the oligomerization of endo-DCPD to exo-tricyclopentadiene (exo-TCPD) compared to a microporous HY catalyst. This is attributed to the abundant acid sites and to the well-developed mesopore structure. Calcination in air was found to be effective for the regeneration of the deactivated MMZY pellet catalyst for synthesis of exo- TCPD from endo-DCPD.

The in-situ catalytic fast pyrolysis of pinecone over HY catalysts, HY(30; SiO2/Al2O3), HY(60), and 1% Ni/HY(30), was studied by TGA and Py-GC/MS. Thermal and catalytic TGA indicated that the main decomposition temperature region of pinecone, from 200 to 400 °C, was not changed using HY catalysts. On the other hand, the DTG peak heights were differentiated by the additional use of HY catalysts. Py-GC/MS analysis showed that the efficient conversion of phenols and other oxygenates formed from the pyrolysis of pinecone to aromatic hydrocarbons could be achieved using HY catalysts. Of the HY catalysts assessed, HY(30), showed higher efficiency in the production of aromatic hydrocarbons than HY(60) because of its higher acidity. The aromatic hydrocarbon production was increased further by increasing the pyrolysis temperature from 500 to 600 °C and increasing the amount of catalyst due to the enhanced cracking ability and overall acidity. The use of 1% Ni/HY(30) also increased the amount of monoaromatic hydrocarbons compared to the use of HY(30) due to the additional role of Ni in enhancing the deoxygenation and aromatization of reaction intermediates.

A low cost alkaline catalyst of dolomite (CaMg(CO3)2) was used to stabilize acacia sawdust bio-oil mixed with methanol. The upgrading efficiency was evaluated in terms of the total acid number (TAN) and viscosity. A change in the dolomite calcination temperature from 700 to 900 °C led to a significant change in the TAN and viscosity of the methanol-added bio-oil. Dolomite activated at higher temperatures had larger amounts of active CaO and MgO species due to the enhanced decarboxylation of calcium and magnesium carbonates. An increase in the dolomite content (1-5 wt%) decreased the TAN value of bio-oil remarkably. A thermal aging test of the methanol-added bio-oil upgraded using dolomite (calcined at 900 °C) at 50 °C for 24 h was carried out by storing the bio-oil at 80 °C for one week. Although the TAN value increased after the aging process, it was still lower than the TAN of raw bio-oil. In addition, increasing the methanol content (10-30 wt%) decreased the TAN and viscosity of the bio-oil significantly.

This study focused on the effect of the incorporation of aluminum on the catalytic performance of KIT-6 in the norbornadiene cyclodimerization reaction. An Al-KIT-6 material synthesized through Al grafting over siliceous KIT-6 was shown to have a well-ordered mesoporous structure and a large pore size. The grafting of Al onto siliceous KIT-6 generated weak acid sites consisting of Lewis acid sites and Bronsted acid sites. Cyclodimerization of norbornadiene was carried over Al-KIT-6 catalysts in a batch reactor in order to compare their activity with that of the Al-MCM-41 catalyst. The activity of norbornadiene cyclodimerization over the Al-KIT-6 catalyst was higher than that over the Al-MCM-41 catalyst, which could be attributed to the larger pore diameters of the Al-KIT-6 catalyst. The acidity and the catalytic activity of the Al-KIT-6 catalyst as used here could easily be recovered through filtering and calcination in an air atmosphere at 550 °C.

Co-feeding a hydrogen-rich material with biomass feedstock is an effective approach to enhance the pyrolysis process efficiency. In this research, the effect of methane (H/C eff ratio of 4) co-feeding on product selectivity of catalytic pyrolysis of lignin and yellow poplar was studied at 600 °C using HY and HZSM-5/metal-modified HZSM-5 as in-situ and ex-situ catalysts, respectively. Fe, Cu, Zn, and Mo with a 3 wt% loading and Ni with 1, 3, and 5 wt% loadings were incorporated into HZSM-5 by incipient wetness impregnation method. Compared to the nitrogen pyrolysis atmosphere, methane enhanced significantly the level of hydrocarbon (BTEX, benzene derivatives and polyaromatics) production from the cellulose and hemicellulose fractions of biomass. Lignin was selectively converted to alkylphenols in catalytic pyrolysis under methane atmosphere. The maximum hydrocarbon yield of 5.86 wt% was obtained from catalytic pyrolysis of yellow poplar using HY ( in-situ ) and 1 wt% Ni/HZSM-5 ( ex-situ ) as catalysts, mainly due to the effects of Ni on enhanced methane activation and an increase in the acid site density of HZSM-5. Meanwhile, the coke content of HZSM-5 was increased in both lignin and yellow poplar pyrolysis by replacing the pyrolysis atmosphere of nitrogen with methane.

The two-step hydrodeoxygenation of pine sawdust pyrolysis oil, or bio-oil, is performed using pairs of first-step hydrotreating and second-step hydrodeoxygenating catalysts. The reaction results demonstrate that the combination of hydrotreating carbon-supported 5 wt% Pd (5 wt% Pd/C) and hydrodeoxygenating tungstate-zirconia-supported 3 wt% Ru (3 wt% Ru/WZr) catalysts produced the highest yield of oil products and the lowest yield of cokes and tars. The hydrodeoxygenated liquid products are further analyzed using FT-IR, which indicates the removal of carbonyls and hydroxyls along with an increase of methyls. The roles of hydrotreating Pd/C are further studied using GC/MS results of the hydrotreated liquid products; these results indicate that the hydrogenation of carbonyls to alcohols and the saturation of furans occur during the first step of the hydrotreating process. The removal of carbonyls and unsaturated furans can suppress their strong adsorption to noble metal surfaces and then their carbonization to cokes.

In this study, the oligomerization of a butene mixture composed of 1-butene, cis-2-butene and trans-2-butene over several types of zeolites in a fixed-bed catalytic reactor at an elevated pressure was studied to produce hydrocarbons in the jet fuel range (C8–C16). Three types of zeolites, HZSM-5, Hβ and HY, were compared to evaluate the performance during the synthesis of jet fuel via the oligomerization of the aforementioned butene mixture. Compared to HY and Hβ, HZSM-5 showed a very stable butene conversion rate with high selectivity to jet-fuel-range hydrocarbon, which could be attributed to high resistance to coke resulting from the pore structure. HZSM-5 (50) shows the best quantitative conversion performance and yield for jet fuel for a time-on-stream of up to 6 h. It was also noted that the branched-to-linear hydrocarbon ratio reached 8.7 over the HZSM-5 (50) catalyst, which is beneficial to improve the cold properties of jet fuel. The present study reveals that HZSM-5 (50) is a potential catalyst for jet fuel synthesis through the oligomerization of butene mixture, exhibiting high stability and a high yield.

This study investigates the effects of Ni impregnation and desilication on HZSM-5 for the hydrodeoxygenation (HDO) of biomass pyrolysis oil. Ni was impregnated in different supporting catalysts, HZSM-5 and desilicated HZSM-5 (DeHZSM-5), and used as catalysts for the catalytic HDO of Geodae-Uksae pyrolyzates. Between HZSM-5(30) and HZSM-5(80), which have different SiO2/Al2O3 ratios (30 and 80), HZSM-5(80) showed the higher desilication efficiency. Ni/DeHZSM-5(80) revealed higher performance on the production of hydrocarbons during the catalytic HDO of Geodae-Uksae pyrolyzates than Ni/HZSM-5(30) because of the increased hydrophobicity, hydrogen reduction efficiency, and mesoporosity of Ni/DeHZSM-5(80) enhanced by the desilication of HZSM-5. Ni/DeHZSM-5(80) also produced larger amounts of esters during the liquid-phase catalytic HDO of Geodae-Uksae pyrolysis oil using supercritical ethanol as a solvent in a high-pressure batch reactor. The two-step catalytic upgrading reaction via the catalytic pyrolysis of Geodae-Uksae over HZSM-5(30) followed by catalytic HDO reaction over Ni/DeHZSM-5(80) enhanced not only the formation of aromatic hydrocarbons and cycloalkanes but also decreased the coke yield on Ni/DeHZSM-5(80).

Mesoporous CuCe-based ternary metal oxides were synthesized using KIT-6 as a hard template through a nano-casting method. The mesoporous CuCe-based metal oxides were applied to the catalytic decomposition of the ammonium dinitramide-based liquid monopropellant. The decomposition onset temperature over the meso-CuCe ternary metal oxides was much lower than that over the CuCeOx catalyst prepared by conventional precipitation method. Higher activity of the meso-CuCe ternary metal oxides is attributed to higher surface area and larger pore size of the meso-CuCe ternary metal oxides than those of the conventional CuCe oxide. The highest activity of meso-CuCeZr catalyst among the meso-CuCe ternary metal oxide catalysts is likely due to the highest mesoporosity.

Strong adsorption of phenolics on zeolite acid sites causes high trapping inside zeolite channels and low catalytic activity of zeolite-supported catalysts in atmospheric pressure hydrodeoxygenation (HDO) of lignin-derived phenolics. This adsorption is more severe at low temperatures, and restricts the atmospheric HDO of phenolics to high reaction temperatures. The purpose of this research was to develop a catalyst with low phenolic trapping potential and high HDO efficiency under mild reaction conditions. Among the tested catalysts (Fe/HBeta, FeReOx/HBeta, Fe/MCM-41, ReOx/MCM-41, FeReOx/MCM-41, Fe/ZrO2 and FeReOx/ZrO2), the novel catalyst of FeReOx/ZrO2 exhibited the highest catalytic efficiency for mild-condition (pressure: 1 atm and temperature x/ZrO2 displayed remarkably enhanced performance, and its catalytic activity for the HDO of m-cresol at 350 °C was almost twice higher than that of Fe/HBeta(38) at 500 °C. Importantly, FeReOx/ZrO2 revealed a high HDO efficiency (BTX yield of 50.5 wt% with phenolic trapping below 5 wt%) at a low temperature of 250 °C, while Fe/HBeta(38) almost lost its entire catalytic activity at this temperature, and gave a low BTX yield of 3.0 wt% with a high trapped phenolic yield of 83.1 wt%. The remarkable catalytic activity of FeReOx/ZrO2 in the HDO of phenolics at atmospheric pressure and temperatures as low as 250 °C is a result of its mesoporosity and oxophilicity as well as its well-balanced acidity induced by both rhenium oxide and zirconia support causing a high dehydration efficiency.

The atmospheric distillation residue (ADR) of cork oak (CO) pyrolysis oil was used as the co-feeding material for the catalytic pyrolysis of CO over HZSM-5 catalysts to improve the formation of aromatic hydrocarbons. Although the non-catalytic copyrolysis of CO and ADR did not improve the formation of aromatic hydrocarbons, the catalytic copyrolysis of CO and ADR promoted the synergistic formation of aromatic hydrocarbons. HZSM-5(30), having a lower SiO2/Al2O3(30), showed better performance for the formation of aromatic hydrocarbons than HZSM-5(80) because of its higher acidity. The catalytic copyrolysis of CO and ADR also decreased the formation of coke. The largest quantity of aromatic hydrocarbons was obtained from the catalytic copyrolysis of CO and ADR over HZSM-5 (30) at 600 °C, whereas the lowest coke yield was achieved at 700 °C. When the catalyst to sample ratio was increased from 2:1 to 5:1, the synergistic formation of aromatic hydrocarbons was limited, resulting in a lower experimental yield of aromatic hydrocarbons than the theoretical yield. A lower coke yield was also achieved at a high catalyst to sample ratio (5:1).

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.

The catalytic co-pyrolysis of epoxy-printed circuit board (e-PCB) and thermoplastics, high density polyethylene (HDPE) and polypropylene (PP), over HZSM-5 and HY was performed using a thermogravimetric analyzer and pyrolyzer-gas chromatography/mass spectrometry. The catalytic pyrolysis of e-PCB over both HZSM-5 and HY eliminated the brominated compounds, mainly bromo-phenols and -bisphenol As, to some extent. The co-feeding of HDPE and PP on the catalytic pyrolysis of e-PCB over both HZSM-5 and HY revealed different debromination efficiencies due to the properties of the thermoplastics and catalysts. A comparison of HY(80) and HZSM-5(80) with the same SiO2/Al2O3 ratio (80) revealed HY(80) had a better elimination efficiency of brominated compounds during the catalytic co-pyrolysis of e-PCB and HDPE or PP because of its larger pore size than HZSM-5(80). The lowest bromine content was achieved when HDPE and HY(30) were used as the co-feeding reactant and catalyst on the pyrolysis of e-PCB due to the large pore size and high acidity of HY(30), allowing the easier diffusion of large molecular brominated bisphenol A and HDPE molecules into the pores of the catalyst and efficient catalytic intermolecular reactions in the pores of the catalyst. The catalytic co-pyrolysis of e-PCB and HDPE over HY(30) also produced large amounts of mono-aromatic hydrocarbons and mono-phenol, which can be used as fuels or chemical feedstock.

The catalytic pyrolysis of biomass using zeolites as catalysts is a promising technique for the production of renewable chemicals and fuels. On the other hand, the low effective hydrogen to carbon ratio of biomass results in a hydrogen-deficient hydrocarbon pool inside the catalyst and in turn the formation of carbonaceous deposits, which causes catalyst deactivation. The catalytic copyrolysis of cellulose and polypropylene was conducted using ZSM-5, desilicated ZSM-5, and Al-SBA-15. The co-feeding of polypropylene with cellulose led to the enhanced formation of aromatic hydrocarbons due to the increased hydrogen content of feedstock and the interaction between the cellulose-derived furans and olefins obtained from polypropylene. Microporous zeolites resulted in the production of more aromatic hydrocarbons compared to mesoporous Al-SBA-15. In addition, desilicated ZSM-5 showed better catalytic performance than the parent ZSM-5 due to the presence of larger channels that facilitate the diffusion of compounds with a wider range of molecular sizes.

Catalytic co-pyrolysis of polypropylene and Laminaria japonica was carried out using Py-GC/MS and a fixed-bed reactor over different catalysts: HZSM-5, mesoporous MFI, Pt/mesoporous MFI, and mesoporous Al-SBA-16. The contents of oxygenates, acids, and wax species were reduced substantially by catalytic upgrading, whereas the contents of aromatics and light hydrocarbons in the gasoline and diesel range were significantly increased, enhancing the economic value of the bio-oil. Among the catalysts used in this study, Pt/mesoporous MFI showed the highest catalytic upgrading capability, which was attributed to large pore size, strong Bronsted acid sites, and the catalytic effect of added Pt.

Tungstated zirconia (WO3/ZrO2 with WO3 loadings of 9.9 (WZ9.9), 15.5 (WZ15.5), and 15.7 wt% (WZ15.7)) and Amberlyst (15, 35, 36, 39 and 45) catalysts were employed to upgrade pyrolysis bio-oil of acacia sawdust through an esterification reaction using methanol at atmospheric pressure and room temperature or 80 °C. The upgrading efficiency was evaluated by measuring the total acid number (TAN) and viscosity. The viscosity and TAN of the resulting upgraded bio-oil were found to be dependent on the calcination temperature of the WO3/ZrO2 catalysts. At room temperature, the largest decrease in viscosity and TAN of the bio-oil and methanol mixture was obtained using WZ9.9 tungstated zirconia calcined at 900 °C. An increase in reaction temperature to 80 °C improved the flowability and TAN of the methanol-added bio-oil using WZ9.9 activated at 900 °C. The product distribution of the bio-oil upgraded using methanol revealed esterification to be the dominant reaction pathway under the reaction conditions of this study. When the ether extracted bio-oil was upgraded at 80 °C using methanol over catalysts, the Amberlyst catalysts were found more effective than tungstated zirconia catalysts in enhancing the esterification reaction and reducing TAN.

The activities of HY, Hbeta, HZSM-5 and mesoporous Al-MCM-41 catalysts were evaluated during the dimerization of bicyclo[2.2.1]hepta-2,5-diene (norbornadiene, NBD). This study focuses on the effects of the pore structure and acidity of the catalysts on the NBD dimerization reaction. When conducting the NBD dimerization reaction over the HY, Hbeta, HZSM-5 and Al-MCM-41 catalysts, it was confirmed that NBD dimer (NBDD) synthesis could be facilitated at a temperature of 250 °C, whereas NBD scarcely reacts through a thermal reaction without a catalyst. Although the NBD conversion rates of the four catalysts are nearly identical after a 12-h reaction, the HY zeolites showed much higher selectivity to NBDD than those with the Hbeta, HZSM-5 and Al-MCM-41 catalysts. The HY catalyst showed the highest yield, reaching 41.5 wt% after a 12-h reaction. The higher selectivity of the HY catalyst during the dimerization of NBD could be explained in terms of its appropriate pore structure and by the higher concentration of Bronsted acid sites. The present study reveals that the HY zeolite is a potential heterogeneous catalyst for NBDD synthesis through the dimerization of NBD at a high yield.

Silicoaluminophosphate molecular sieve, SAPO-11, was applied for the first time to the catalytic pyrolysis of xylan and dealkaline lignin. The isothermal fast catalytic pyrolysis of xylan and dealkaline lignin over different amounts of SAPO-11 and their product analysis were performed concurrently using a pyrolyzer GC/MS. Large amounts of oxygenated pyrolyzates produced from the non-catalytic pyrolysis of xylan at 500 °C were converted to furans, light hydrocarbons, and aromatic hydrocarbons using SAPO-11. When the catalyst to sample ratio was increased from 1:1 to 5:1 and 10:1, the selectivity toward aromatic hydrocarbons was increased dramatically. Phenolic compounds, such as guaiacols and vanillin, were the main products of the non-catalytic pyrolysis of dealkaline lignin. These phenolic compounds were upgraded efficiently into aromatics by the catalytic pyrolysis of dealkaline lignin over SAPO-11. By increasing the catalyst to sample ratio from 1:1 to 10:1, much larger amounts of aromatic hydrocarbons were obtained due to the increased catalyst acid sites. A phenolic pool mechanism was suggested as the major reaction pathway for the catalytic pyrolysis of dealkaline lignin over SAPO-11.

The change in acidity of pyrolysis bio-oil was investigated using the catalytic pyrolysis of cork oak over zirconia synthesized by supercritical hydrothermal synthesis using a fixed bed reactor. Catalytic pyrolysis over zirconia reduced the content of acetic acid considerably and showed high selectivity to ketones and high-value-added aromatic compounds.

Amorphous spherical-shaped copper–manganese oxide for the catalytic combustion of benzene were successfully obtained by a wet granulation process under different calcination temperatures. The low-temperature (400 °C) calcined catalysts—which showed a larger BET specific surface area, low temperature reducibility, and an amorphous phase—were more active for the catalytic combustion of benzene than the high-temperature calcined catalyst which underwent the amorphous to crystalline phase transition. The catalytic activity tests, depending on the operating parameters, suggested that amorphous spherical-shaped copper–manganese oxide have potential applications for remedying VOC pollution.

The effects of the torrefaction of cellulose on catalytic co-pyrolysis with polypropylene (PP) over HZSM-5 and HBeta catalysts were examined in a pyrolyzer-GC/MS/TCD/FID system. Torrefied cellulose produced larger quantities of aromatic hydrocarbons during catalytic pyrolysis over both BETA and HZSM-5 catalysts than raw cellulose due to the change in crystallinity and structure of cellulose. Among the catalysts tested, HZSM-5(30) showed the highest performance for the production of aromatic hydrocarbons from the catalytic pyrolysis of torrefied cellulose. The synergy effect for the production of aromatic hydrocarbons was also observed on the catalytic co-pyrolysis of torrefied cellulose and PP over HZSM-5, even when a low catalyst to sample ratio was applied. The maximum BTEXs yield (33.4 wt.%) was achieved from the catalytic co-pyrolysis of torrefied cellulose and PP at a catalyst to sample ratio of 3/1 and a torrefied cellulose to PP ratio of 1/3.

The removal of acetaldehyde, which is one of main components of food waste odor was investigated using biomass char as a nanoporous carbon absorbent. The biomass char adsorbent obtained from the pyrolysis of Geodae-Uksae was modified by the water and KOH treatment. The modified char absorbent had a higher acetaldehyde removal efficiency than nanoporous CMK-8 possibly due to its high oxygen and nitrogen functional groups.

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.

The two-stage catalytic pyrolysis of lignin over in-situ natural zeolite (NZ) and ex-situ HZSM-5 was examined using a tandem fixed bed reactor. The physicochemical properties of the catalysts, HZSM-5 and NZ, were characterized by N2 adsorption-desorption and temperature programed desorption of ammonia. The overall performance for the catalytic pyrolysis of lignin was evaluated by the comparing lignin conversion, aromatic formation, and amount of coke deposited from the two-stage catalytic pyrolysis with those from a single-stage catalytic pyrolysis with ex-situ HZSM-5. Compared to the single-stage catalytic pyrolysis, the two-stage catalytic pyrolysis produced a larger amount of aromatics with a smaller amount of coke due to the pre-catalytic effect of NZ. These positive effects caused by the use of the two-stage catalyst were maximized by increasing the amounts of in-situ natural zeolite and the temperature of the ex-situ HZSM-5 catalyst bed to 600 °C.

Particle board and polypropylene (PP) at a mixing ratio of 1:1 were copyrolyzed over two Al-MCM-48 catalysts with Si/Al ratios of 20 and 80. The catalyst characteristics were examined by measuring the Brunauer-Emmett-Teller surface area, temperature programmed desorption of ammonia, and X-ray diffraction. The main pyrolysis products of particle board were oxygenates, acids, and phenolics, whereas a large quantity of hydrocarbons within the diesel fuel range was produced from copyrolysis with polypropylene. The catalytic copyrolysis of particle board and PP over the Al-MCM-48 catalysts produced bio-oil with a much larger hydrocarbon content than that from the catalytic pyrolysis of particle board only. The hydrocarbons produced were mainly in the diesel range, highlighting the potential for the production of high-quality fuel.

− Platinum catalysts supported on the mesoporous material synthesized from Y zeolite were applied to synthesis of jet-fuel through n-octadecane hydroupgrading. The mesoporous aluminosolicate, MMZ HY was synthesized using Y zeolite as its framework source. The effect of the addition of Mg to Pt/MMZ HY catalyst for n-octadecane hydroupgrading was investigated. Catalyst characterization was performed with X-ray diffraction, N 2 adsorption, temperature-programmed reduction in hydrogen flow, temperature-programmed desorption of ammonia, and infrared spectroscopy of adsorbed pyridine. The high yield of jet-fuel over the PtMg(2.0)/MMZ HY can be attributed not only to the higher dispersion of Pt metal and higher reducibility, but also the higher amount of acid sites and higher strength of acid sites. The selectivity to iso-paraffin in the jet-fuel fraction could be reached above 80% over the optimized PtMg/MMZ HY catalyst.