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Catalytic co-conversion of Kraft lignin (KL) and linear low-density polyethylene (LLDPE) over mesostructured catalysts was examined using a micro-pyrolyzer equipped with gas chromatography-mass spectrometry/flame ionization detector (MPy-GC/MS/FID). Mesoporous catalysts of Al-SBA-15 and mesoZSM-5 were synthesized and characterized by N2 sorption, ammonia temperature programmed desorption, and X-ray diffraction. The characterization results indicated that mesoZSM-5 had the smaller average pore size (4.10 nm) than Al-SBA-15 (10.70 nm), but its total acidity (both weak and strong acid sites) was much higher than Al-SBA-15. When they were applied as catalysts in the pyrolysis of KL and LLDPE, the mesoZSM-5 exhibited higher catalytic activity for aromatic hydrocarbon production due to its higher acidity and MFI pore structure. Indeed, synergistic synthesis of aromatic hydrocarbons was achieved via the catalytic co-pyrolysis of KL and LLDPE because of the H-donating effect of LLDPE; the experimental yields (GC/MS area; abundance vs. time) of aromatic hydrocarbons in the oils obtained from catalytic co-pyrolysis of KL/LLDPE (1:1) over Al-SBA-15 (8.76 × 107) and mesoZSM-5 (27.58 × 107) were ∼1.5 fold higher than the theoretical yields.

Calcined waste seashell powder from cockles and mussels was used as the pretreatment materials for kraft lignin (KL), and their impacts on the pyrolysis behavior of KL were examined using a laboratory-scale fixed bed reactor and thermogravimetric analysis. The highest intensity of the CaO peak was observed on the XRD patterns of the seashell obtained from the calcination of mussel shells at 800 °C (M8). Char foaming was not detected when the water treated KL/seashell were pyrolyzed at 500 °C. In contrast, severe char foaming and agglomeration were observed when KL alone and a physical mixture of M8 and KL (KL/M8-mix) were pyrolyzed at the same temperature. The pyrolysis of water-treated KL/M8 (KL/M8/water) also produced much higher quality oil than those of KL alone or the KL/M8 mixture, showing higher selectivity to light phenols and aromatics. The decomposition temperature of KL was also decreased using M8 with water due to the catalytic effect of calcium oxide.

Lignocellulosic biomass is an abundant and environment-friendly source for renewable energy production. The value and application of biochar, which is obtained from the thermochemical conversion of biomass, is increasing rapidly because of its high carbon content and porosity. The property of biochar, such as surface area, porosity, and number of functional groups, can be improved by controlling the conditions of biomass conversion, biochar activation, and functionalization methods. The production and activation of biochar as well as its potential use for soil remediation, pollutant adsorption, and biorefinery have been reviewed extensively over recent decades. This paper provides a conceptual approach for biochar production and activation together with its application as a catalyst for biorefineries and the removal of environmental contaminants.

Various MgO impregnated catalysts were used for the catalytic co-pyrolysis (CCP) of cellulose and linear low-density polyethylene (LLDPE) at 600 °C in ambient pressure. Micro reactor-gas chromatography, a semi-batch reactor, was used as a reactor and gas chromatogram/mass spectrometry/flame ionization detector were used for product detection. Three kinds of MgO impregnated catalysts, MgO/Carbon (MgO/C), MgO/Al2O3, and MgO/ZrO2, were prepared by the impregnation of MgO to different supporting material s, C, Al2O3, and ZrO2, respectively. Activities of the three MgO-impregnated catalysts were compared with 1:5 of feedstock to catalyst ratio. MgO/C produced the highest quality oil, which consisted of a large amount of aromatic hydrocarbons during the catalytic pyrolysis (CP) of cellulose. When the MgO catalysts were applied to CCP, the selectivity to aromatic hydrocarbons over MgO/C were 13.42%, which were also much higher than those over the other catalysts, including bulk MgO, demonstrating the effectiveness of the MgO/C catalyst on aromatics formation. Importantly, the experimental BTEXs (benzene, toluene, ethylbenzene, xylenes) yields of CCP over MgO/C were also much higher than the theoretical yields, highlighting the effectiveness of hydrogen-rich LLDPE on the CP of cellulose over MgO/C. Further investigation of the cellulose/LLDPE mixing ratio showed that the amount of BTEXs during the CCP of cellulose and LLDPE could be maximized by adjusting the cellulose to LLDPE mixing ratio to 25:75.

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.

This study examined the catalytic co-pyrolysis of yellow poplar wood and polyethylene terephthalate over basic calcium oxide and acid zeolites, such as HY (SiO2/Al2O3: 30), Hβ (25), HZSM-5 (23), to maximize the yields of aromatics using thermogravimetric analysis and tandem μ-reactor-gas chromatography/mass spectrometry. The maximum decomposition temperature of polyethylene terephthalate on the catalytic thermogravimetric analysis over HZSM-5 (452 °C) was reduced by co-feeding with yellow poplar wood to 444 °C because of its catalytic property and the effective interaction between the catalytic co-pyrolysis intermediates of yellow poplar wood and polyethylene terephthalate. Non-catalytic co-pyrolysis produced smaller amounts of large molecular polyethylene terephthalate pyrolyzates because of the more effective secondary cracking and deoxygenation. Calcium oxide was effective in the deacidification and acid zeolites were efficient in aromatics production during the catalytic co-pyrolysis of yellow poplar wood and polyethylene terephthalate. Among the acid zeolites, HZSM-5 showed the highest efficiency on benzene, toluene, ethylbenzene, and xylenes (BTEXs) production, followed by Hβ and HY because of its strong acidity and proper pore size. The experimental MS intensities of BTEXs obtained from the catalytic co-pyrolysis of yellow poplar wood and polyethylene terephthalate over HZSM-5 (1083 × 106) were larger than their theoretical value (998 × 106). Compared to the single stage catalytic co-pyrolysis of yellow poplar wood and polyethylene terephthalate over ex-situ HZSM-5, the two-stage catalytic co-pyrolysis over in-situ calcium oxide and ex-situ HZSM-5 produced the much larger amounts of BTEXs during seven times sequential experiments.

The issues over increases in energy demand and environmental pollution attributed to excessive use of fossil fuel have been the driving forces of the exploration for eco-friendly resource. Lignocellulosic biomass consisting of carbohydrates and lignin can be a renewable feedstock for replacing fossil fuels in the future because it is a plentiful and carbon neutral material. Especially, lignin, cross-linked phenolic polymers, is a topic of interest owing to its abundant production from pulp/paper industries as well as lignocellulose based biorefinery. The large potential of platform chemicals and biofuels from lignin has opened up an extensive range of opportunities to develop thermal and catalytic conversion technology. Over a few decades, several lignin conversion processes including catalytic pyrolysis, catalytic depolymerization, and catalytic oxidation have been developed to improve target products yields and to suppress side reactions. More recently, lignin-first approaches which maintain carbohydrates intact by selective extraction of lignin as valuable phenolics from whole biomass has been suggested. This review introduces recent ten years progress on thermal and catalytic conversion technology in terms of process type, catalyst development, and target products. This review is expected to offer an influential information for future research into the thermal and catalytic conversion of lignin as well as lignocellulosic feedstock.

A base catalyst is expected to suppress coke formation of the catalyst, leading to less catalyst deactivation and more efficient production of bio-oil. To examine the feasibility of a solid-base catalyst as a lignin pyrolysis catalyst, MgO loaded on supports with different textural, acid, and base properties (i.e. carbon, Al2O3, and ZrO2) was applied. In addition, because the co-processing of biomass with plastic significantly improves the quality of bio-oil in the catalytic pyrolysis process, co-pyrolysis of lignin with linear low-density polyethylene was performed, and the effects of the MgO catalysts were analyzed. Thermogravimetric analysis and a tandem micro-reactor–gas chromatography/mass spectrometry system were used to evaluate the performance of the MgO catalysts in terms of thermal decomposition behavior and yield of monoaromatic hydrocarbons. Overall, MgO supported on carbon (MgO/C) showed the highest yield of aromatic hydrocarbons during the pyrolysis of lignin, due to its well-balanced acid/base sites and high surface area. Also, MgO/C exhibited the strongest positive synergy toward the production of aromatic hydrocarbons during co-pyrolysis, which suggests that a metal oxide with base properties supported on high-surface-area carbon could be an efficient catalyst for producing bio-oil with high energy density fuel additives from the lignin.

Mesostructured aluminosilicates of Al-MSU-F (commercial), Al-SBA-15 (home-made), and mesoMFI (a mesoporous aluminosilicate with MFI structure, home-made), with a silica-to-alumina ratio of 40, were used as catalyst for the in-situ catalytic pyrolysis (CP) of empty fruit bunches (EFB) at 600 °C. The highest selectivity to aromatic hydrocarbons in bio-oil was obtained over mesoMFI due to its higher acidity than Al-SBA-15 and Al-MSU-F. In addition, ex-situ CP of EFB using mesoMFI was compared with in-situ CP; the ex-situ configuration produced higher aromatic hydrocarbons than the in-situ configuration. Meanwhile, in-situ and ex-situ catalytic co-pyrolysis (CCP) of EFB (with a H/Ceff ratio less than 0.3) and polypropylene (PP) (with a high H/Ceff ratio about 2) were carried out using the mesoMFI at 600 °C to investigate the supplementary effect of PP on the deoxygenation of EFB-derived pyrolyzates for producing aromatic hydrocarbons. Ex-situ CCP of EFB/PP (with the mass ratios of 75/25, 50/50, and 25/75) resulted in a lower formation of aromatic hydrocarbons than the in-situ CCP. In addition, the thermal decomposition behavior of EFB, PP, and EFB/PP in non-catalytic and catalytic (mesoMFI) pyrolysis/co-pyrolysis was investigated using thermogravimetric analysis (TGA); use of catalyst reduced the temperature of PP thermal degradation, but did not change the maximum reactivity temperature of EFB degradation.

The concerns over the increasing energy demand and cost as well as environmental problems derived from fossil fuel use are the main driving forces of research into renewable energy. Lignocellulosic biomass comprised of cellulose, hemicellulose, and lignin is an abundant, carbon neutral, and alternative resource for replacing fossil fuels in the future. Solvent liquefaction of lignocellulosic biomass is a promising route to obtain biofuels, bio-based materials, and chemicals using a range of solvents as reaction media under moderate reaction conditions. Recently, several researchers have considered novel approaches for enhancing the process efficiency and economics. This review article reports the state-of-the-art knowledge of lignocellulose liquefaction in the recent three years with the main focus on the feedstock, liquefaction technology, target products, and degradation mechanism of each biomass component. This review is expected to provide an important reference for research into the solvent liquefaction of lignocellulose in the near future.

High density polyethylene (HDPE) was applied as a co-feeding feedstock on the catalytic pyrolysis (CP) of yellow poplar (YP) over mesoporous catalysts, Al-MCM-48 s(SiO2/Al2O3: 23, 80) and Al-MSU-F(SiO2/Al2O3: 82). Compared to the non-catalytic thermogravimetic (TG) analysis of HDPE, catalytic TG analysis of HDPE had much lower decomposition temperatures, 407 °C over Al-MCM-48(23), 432 °C over Al-MCM-48(80) and 446 °C over Al-MSU-F(82). On the other hand, the decomposition temperatures of HDPE increased up to 460 °C over Al-MCM-48(23), 482 °C over Al-MCM-48(80), and 492 °C over Al-MSU-F(82) by applying the mixture of HDPE and YP as a feedstock on the catalytic TG analysis. The experimental yields of aromatic hydrocarbons obtained from the catalytic co-pyrolysis (CCP) of YP and HDPE over mesoporous catalysts were much higher than their theoretical yields. Among mesoporous catalysts, Al-MCM-48(23) produced the larger amount of aromatic hydrocarbons (2.89%) on the CCP of HDPE and YP than those (2.34–2.48%) over Al-MCM-48(80) and Al-MSU-F(82) and also provided the highest synergistic effect on the formation of aromatic hydrocarbons. The higher synergistic effect over Al-MCM-48(20) was achieved by applying the higher YP/HDPE ratio in the feedstock (3/1), higher catalyst/sample ratio (4/1), and higher reaction temperature (600 °C).

Catalytic pyrolysis (CP) of waste plastic film over mesoporous catalyst, Al-MSU-F, was investigated using polystyrene (PS) and polyethylene terephthalate (PET) as the model plastic resins. Thermogravimetric analysis of PS and PET indicated that their decomposition temperatures were shifted to the much lower temperature owing to the high diffusion ability of reactant into mesopore of Al-MSU-F. Py-GC/MS analysis for the CP of PS and PET revealed that the large amount of aromatics can be obtained by the use of Al-MSU-F and it was further increased by using the higher catalyst/polymer ratio. CP products of PET over Al-MSU-F showed the high selectivity to mono aromatic hydrocarbons. Meanwhile, those of PS revealed the high selectivity to poly aromatics.

The catalytic copyrolysis of torrefied cork oak (TOak) and high density polyethylene (HDPE) over mesoporous HY catalysts was performed using a tandem μ-reactor-gas chromatograph/mass spectrometry/flame ionization detector. Two types of mesoporous HY catalysts with different acidity, MesoHY-1 and MesoHY-2, were prepared by pseudomorphic synthesis with various surfactant ratios. For comparison, a commercial microporous HY was also used as a catalyst. The properties of the catalysts were measured by N2-sorption, X-ray diffraction, and NH3-temperature programmed desorption. Compared to the catalytic pyrolysis of cork oak (Oak), that of TOak produced a larger amount of mono aromatic hydrocarbons (MAHs) over all HY catalysts. The catalytic copyrolysis of TOak and HDPE over micropore HY and MesoHY-1 produced a larger amount of MAHs than that over MesoHY-2 due to the higher acidities. Although both micropore HY and MesoHY-1 have similar acidity, MesoHY-1 showed stronger synergy for the formation of MAHs on catalytic copyrolysis than micropore HY owing to its larger pore, which allows the easier diffusion of HDPE reaction intermediates into the pore of the catalysts.

The catalytic co-pyrolysis of biomass carbohydrates and LLDPE over mesoporous catalysts, mesoporous ZSM-5 (MZSM-5) and Al-SBA-15, was investigated using a tandem micro reactor-GC/MS system. The properties of the synthesized MZSM-5 and Al-SBA-15 were characterized by N2-sorption, X-ray diffraction, and NH3-temperature programmed desorption. Compared to Al-SBA-15, MZSM-5 showed better performance in the production of aromatic hydrocarbons during the catalytic pyrolysis of carbohydrates (avicel (cellulose) and xylan) due to the stronger acidity of MZSM-5. The catalytic co-pyrolysis of carbohydrates and LLDPE showed synergistic aromatic formation due to the supply of more effective hydrocarbon pool species and an efficient Diels-Alder reaction between the pyrolyzates of the carbohydrates and LLDPE. When avicel was torrefied, the aromatic yields were increased further in catalytic pyrolysis/co-pyrolysis.

Egg-shell-type pellet catalysts were prepared by selectively placing nickel and/or ruthenium on the outer region (shell) of alumina pellets so that the active components can be utilized effectively in steam methane reforming (SMR) reaction with high gas-hourly space velocity conditions. To ensure the reproducibility of catalyst preparation, we evaluated two types of commercial alumina pellets. And, we finally selected one commercial alumina pellet, which had uniform pores distribution. The thickness of the ruthenium-shell can be controlled by optimizing the evaporation temperature and rotating speed while preparing an ‘egg-shell-type’ 1 wt. % Ru/alumina catalyst. When applied to a SMR reaction, as the space velocity of the reactant increased in SMR reaction, ‘egg-shell-type’ 1 wt. % Ru/alumina catalyst showed a higher methane conversion than a ‘homo-type’ 1 wt. % Ru/alumina pellet catalyst, in which the active metal was uniformly dispersed in the whole region of pellet. Since ruthenium is a costly noble metal, we prepared a Ni/Ru bimetal catalyst [‘egg-shell-type’ 5 wt. % Ni/0.7 wt. % Ru bimetal catalyst] substituting nickel for some portion of the ruthenium in order to increase the economic feasibility. The bimetal Ni/Ru catalyst showed even better CH4 conversion than the egg-shell-type catalyst containing ruthenium only. We also confirmed that the egg-shell-type catalyst effectively utilized its active components in the SMR reaction.

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.

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 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.

The thermal and ex-situ catalytic pyrolysis of different citrus peels, Citrus paradisi peel, Citrus sinensis peel, Citrus unshiu peel, and Citrus limon peel, were studied by thermogravimetric, evolved gas analysis–mass spectrometry and tandem micro-reactor–gas chromatograph/mass spectrometry analyses. Kinetic analysis revealed more complicated reaction steps and a wider range of activation energies of citrus peels than those of wood powder due to the presence of pectin in the citrus peels. Large amounts of methanol formation from each citrus peel were also recorded by evolved gas analysis–mass spectrometry and fast pyrolysis–gas chromatograph/mass spectrometry analyses at the main decomposition temperature of pectin, between 150 and 250 °C. Mesoporous MFI was found to be a more effective catalyst for the production of mono aromatic compounds (benzene, toluene, ethylbenzene, and xylene; 3.06–4.17 C%) and light olefins (ethene, propene, butene, and butadiene; 8.13–9.13 C%) than Al-MCM-41 (mono aromatic compounds 0.67–0.93 C% and light olefins 3.61–4.58 C%) because of its higher catalytic activity in deoxygenation and aromatization due to the stronger acidity of mesoporous MFI. The yield of mono aromatic compounds over mesoporous MFI was highest from C. paradisi peel (4.17 C%), followed in order by C. sinensis peel (3.83 C%), C. unshiu peel (3.61 C%), and C. limon peel (3.06 C%), due mainly to the different contents and properties of pectin in each citrus peel. The higher activities of mesoporous MFI than Al-MCM-41 were also maintained during the 7 times sequential catalytic pyrolysis of C. paradisi peel, demonstrating the stability of mesoporous MFI catalyst.

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.

This study focused on the simultaneous removal of NO and SO2 from an industrial flue gas stream. To evaluate the removal efficiency of NO and SO2 using O3 and NH3, the consumption of two reactants (O3 and NH3) in line with the conversion of NO and SO2 was quantified experimentally. In addition, NO and SO2 were converted to valuable fertilizers, NH4NO3 and (NH4)2SO4. To identify a principle strategy to enhance the generation of fertilizer, Fourier transform infrared spectroscopy was used to examine the reaction mechanisms for the formation of NH4NO3 and (NH4)2SO4. Acceleration of SO2 oxidation could be achieved effectively by adding NO to a gas mixture of SO2, NH3, and O3. The formation of HNO3 might be enhanced by the simultaneous feeding of NO and SO2. Particle generation was also 10 times higher for NH3/(NO + SO2) than for NH3/NO and for NH3/SO2, which is a prominent feature of this study. Moreover, the introduction of steam had a positive influence on particle generation. This method offers dual applications for NO and SO2 removal from a flue gas stream and direct fertilizer generation.

Emulsification is a cost effective and simple method to use pyrolysis oil (or bio-oil) along with diesel as an emulsified fuel. Several combinations of emulsifiers, such as Span 80 and Atlox 4916, Span 80 and Zephrym PD3315, and Atlox 4916 and Zephrym PD3315, were tested to obtain stable emulsions. Two set of reactors (ultrasonicator and agitator-based mechanical reactor system) were used for the process. The ether-extracted pyrolysis oil (EEO), emulsifier, and diesel content of 10%–15%, 3%, and 82–87% were exposed to an ultrasonic power of 40% and with an agitation rate of 900 rpm. The emulsions obtained using Span 80 and Zephrym PD3315 showed stratification within 10 min. The emulsions for Span 80 and Atlox 4916 with a ratio of 3/15/82 for Emulsifer/EEO/Diesel, and for Atlox 4916 and Zephrym PD3315 emulsifiers with a ratio of 3/10/87 for Emulsifer/EEO/Diesel remained stable for more than 15 days. The functional groups analysis showed the stability of the emulsion for Span 80 and Atlox 4916, whereas a change in the absorbance intensity was observed when Atlox 4916 and Zephrym PD3315 were used, indicating stratification.

Catalytic co-pyrolysis (CCP) of spent coffee ground (SCG) and cellulose over HZSM-5 and HY was characterized thermogravimetrically, and a catalytic pyrolysis of two samples was conducted using a tandem micro reactor that directly connected with gas chromatography-mass spectrometry. To access the more fundamental investigations on CCP, the effects of the zeolite pore structure, reaction temperature, in-situ/ex-situ reaction mode, catalyst to feedstock ratio, and the SCG and cellulose mixing ratio were experimentally evaluated. The temperature showing the highest thermal degradation rate of cellulose with SCG slightly delayed due to the interactions during the thermolysis of two samples. HZSM-5 in reference to HY produced more aromatic hydrocarbons from CCP. With respect to the reaction temperature, the formation of aromatic hydrocarbons increased with the pyrolytic temperature. Moreover, the in-situ/ex-situ reaction mode, catalyst/feedstock, and cellulose/SCG ratio were optimized to improve the aromatic hydrocarbon yield.

The additional use of red mud (RM) on the catalytic fast co-pyrolysis (CFCP) of organosolv lignin (OL) and polypropylene (PP) over ex-situ HZSM-5 was investigated using a tandem micro reactor system. Non-catalytic fast co-pyrolysis of OL and PP increased their decomposition efficiency owing to the effective interactions. The in-situ catalytic fast pyrolysis (CFP) of OL over RM led to the enhanced conversion of large molecular OL pyrolyzates with the additional production of aromatic hydrocarbons. The in-situ CFCP of OL/PP over RM resulted in a further increase in the cracking efficiency of OL/PP pyrolyzates as well as an increase in the aromatics formation efficiency owing to the effective interactions between their CFP intermediates. Furthermore, the application of RM in 1st in-situ catalytic reactor was found to be the optimal catalyst system because the in-situ CFCP of OL/PP over RM can enhance the formation of the proper hydrocarbons precursors for the production of aromatics over ex-situ HZSM-5 in 2nd reactor. Compared to the one-step CFCP of OL/PP over ex-situ HZSM-5, two-step CFCP of OL/PP over in-situ RM and ex-situ ZSM-5 maintained the higher aromatics formation during the 7 times sequential reaction due to the slow deactivation of ex-situ HZSM-5.

The fast pyrolysis of waste lignin derived from biobutanol production process was performed to determine the optimal pyrolysis conditions and pyrolysis product properties. Four types of pyrolysis reactors, e.g.: micro-scale pyrolyzer-gas chromatography/mass spectrometry, lab and bench scale fixed bed (FB) reactors, and bench scale rotary kiln (RK) reactor, were employed to compare the pyrolysis reaction conditions and product properties obtained from different reactors. The yields of char, oil, and gas obtained from lab scale and bench scale reactor were almost similar compared to FB reactor. RK reactor produced desirable bio-oil with much reduced yield of poly aromatic hydrocarbons (cancer precursor) due to its higher cracking reaction efficiency. In addition, char agglomeration and foaming of lignin pyrolysis were greatly restricted by using RK reactor compared to the FB reactor.

The catalytic copyrolysis of waste particle board (WPB) and polypropylene (PP) was investigated for the first time over HY (5.1), HY (30), H-Beta and Ga/H-Beta catalysts. The catalysts were characterized by BET and NH3-TPD analyses. The catalytic pyrolysis of the WPB increased the production of gas products (CO, CO2, C1–C4) compared to non-catalytic pyrolysis. Acids and levoglucosan, which are the main components of bio-oil produced from non-catalytic pyrolysis, were converted to more valuable aromatics, phenolics, and furans through dehydration, deoxygenation and aromatization. The most abundant products from the copyrolysis of WPB and PP were large-molecular-mass hydrocarbons (≥C10). However, catalytic copyrolysis increased the yields of small-molecular-mass hydrocarbons in the gasoline range, aromatics and phenolics. The water content in bio-oil was reduced significantly by copyrolysis with PP, contributing to the improvement in oil quality. HY (5.1) with the largest number of acid sites showed higher catalytic activity than HY (30) and H-Beta because the decomposition and reforming reactions during catalytic copyrolysis occurred on the acid sites of the catalysts. Ga/H-Beta showed even higher selectivity toward the aromatics than H-Beta despite the smaller quantity of acid sites, suggesting that Ga promoted the dehydrocyclization of the reaction intermediates.

Three microporous zeolites with different structures, HZSM-5 (Si/Al2 = 23), Hβ (Si/Al2 = 25) and HY (Si/Al2 = 30), were assessed for the first time for the catalytic fast pyrolysis of Geodae-Uksae-1, a variety of Miscanthus sacchariflorus. In non-catalytic pyrolysis, the temperature for the maximum bio-oil yield was 500 °C, which allowed sufficient conversion of the solid to the vapor phase and suppressed the decomposition reactions in the vapor phase. Using the catalysts, the bio-oil yield decreased with significant changes in composition as a result of active deoxygenation and cracking reactions. This led to the release of CO2, CO and C1–C4 hydrocarbons to the gas phase. In the bio-oil composition, the proportions of phenolics, mono-aromatics and polycyclic aromatic hydrocarbons (PAHs) increased, whereas those for acids, oxygenates and furans decreased. In particular, the use of HZSM-5 led to the largest proportion of mono-aromatics with a minimized coke production, since it had higher acidity, higher shape selectivity, and smaller pore size than the other catalysts. With both Hβ and HY catalysts, the formation of PAHs in the bio-oil and coke on the catalyst surface was significantly high. The proportion of light phenolics, such as alkyl phenolics, also increased with the HY catalyst.

Unilamellar mesoporous MFI nanosheets (UMNs) were, for the first time, applied to the catalytic pyrolysis of the constituents of lignocellulosic biomass: cellulose, hemicellulose and lignin. A representative mesoporous catalyst, Al-SBA-15, was also applied to the same process for the purpose of comparison. The catalysts were characterized by N 2 adsorption–desorption, X-ray diffraction, temperature programmed desorption of ammonia, and transmission electron microscopy. The synthesized UMN catalyst was composed of a random assembly of zeolite nanosheets with a thickness of 2.5 nm. UMN was shown to have strong Bronsted acid sites, whereas Al-SBA-15 had weak acid sites. Catalytic pyrolysis experiments were carried out using Py-GC/MS. The product distribution was analyzed in order to evaluate catalytic activity. Acidity had a considerable influence on catalytic activity; UMN, with a higher acidity than Al-SBA-15, exhibited higher activities for cracking and deoxygenation, producing bio-oil with a lower oxygen content and with a better overall quality. Levoglucosan, which was the main product of the non-catalytic pyrolysis of cellulose, was converted to aromatics and furans on the acid sites of the catalysts. Ketones, alcohols and cyclo-compounds, the main products of the non-catalytic pyrolysis of xylan, were also converted to aromatics and furans by catalytic upgrading. The main products of the non-catalytic pyrolysis of lignin were phenolics, which were converted to aromatics and lighter phenolics (alkyl phenolics and methoxy phenolics) in the presence of catalysts. Increasing the catalyst dose improved the quality of the product oil even further.

The pyrolysis characteristics of construction waste wood were investigated for conversion into renewable liquid fuels. The activation energy of pyrolysis derived from thermogravimetric analysis increased gradually with temperature, from 149.41 kJ/mol to 590.22 kJ/mol, as the decomposition of cellulose and hemicellulose was completed and only lignin remained to be decomposed slowly. The yield and properties of pyrolysis oil were studied using two types of reactors, a batch reactor and a fluidized-bed reactor, for a temperature range of 400–550 °C. While both reactors revealed the maximum oil yield at 500 °C, the fluidized-bed reactor consistently gave larger and less temperature-dependent oil yields than the batch reactor. This type of reactor also reduced the moisture content of the oil and improved the oil quality by minimizing the secondary condensation and dehydration. The oil from the fluidized-bed reactor resulted in a larger phenolic content than from the batch reactor, indicating more effective decomposition of lignin. The catalytic pyrolysis over HZSM-5 in the batch reactor increased the proportion of light phenolics and aromatics, which was helpful in upgrading the oil quality.

n -Dodecane was hydroisomerized over Pt supported on Y zeolites with different acid characteristics in a batch reactor. The Y zeolites used were NaY, HY (SiO 2 /Al 2 O 3 = 5.1), HY (SiO 2 /Al 2 O 3 = 80), and HY (SiO 2 /Al 2 O 3 = 200). NaY was ion exchanged with NH 4 Cl to impart acidity. HY (SiO 2 /Al 2 O 3 = 5.1) and HY (SiO 2 /Al 2 O 3 = 80) were silylated to modify their acidity. HY(80) and NaY(5.1) zeolites were examined by XRD and NMR methods only, while Pt/NaY and Pt/HY samples were subjected to investigation, besides XRD method, by N 2 adsorption/desorption, NH 3 TPD, and FT-IR methods. For NaY, HY (SiO 2 /Al 2 O 3 = 5.1), HY (SiO 2 /Al 2 O 3 = 80) and HY (SiO 2 /Al 2 O 3 = 200), the conversion of n -dodecane decreased with increasing SiO 2 /Al 2 O 3 , whereas selectivity of isomerization increased with increasing SiO 2 /Al 2 O 3 . HY (SiO 2 /Al 2 O 3 = 80) showed the best hydroisomerization activity. The catalytic activities of NaY and HY (SiO 2 /Al 2 O 3 = 5.1) were enhanced significantly by ion-exchange and silyation, respectively. The effects of temperature, pressure and Pt loading on the catalytic activity were also investigated.

Threat of global warming and imminent exhaustion of fossil fuels call for development of alternative carbon-neutral energy sources. Among others, bio-oil, which can be produced from various biomass, can be used not only as an alternative fuel but also as a feedstock for production of high-value chemicals. In this study, the potential of wild reed growing in Suncheon Bay Ecological Park area as a bio-energy source was evaluated. Fast pyrolysis of reed for bio-oil production was carried out using a lab-scale reactor system. The effects of pyrolysis conditions were investigated. The produced gas, liquid and solid products were analyzed. The effect of carrier gas flow rate was shown to be not significant. The most important parameter determining the product yields was shown to be the reaction temperature in this study. The bio-oil yield was highest (52%) at 520 °C. The bio-oil yield was higher and the char yield was lower for a larger sample particle size, possibly due to the enhanced heat transfer to individual particles for larger particles packed loosely. The bio-oil was shown to be comprised of acids, alcohols, ketones, aldehydes, phenolics, aliphatic hydrocarbons, and aromatics, with phenolics and aromatics accounting for considerable fractions. The fast pyrolysis of reed is expected to be useful for obtaining valuable chemicals.

Considerable attention has been given to development of renewable energy due to imminent exhaustion of fossil fuels and environmental concerns over global warming. Bio-oil is recognized to be a promising alternative energy source because many different kinds of biomass, including agricultural residues, forest residues, organic waste, and biomass crops, can be used to produce bio-oil. In particular, agricultural residues are abundant biomass resources in South Korea that are usually composted, burned, or abandoned. In this study, the pyrolysis characteristics of two different agricultural residues, red pepper stem and garlic stem, were investigated to evaluate their potential as sources of bio-oil and chemicals for industry. Fast pyrolysis of these agricultural residues was carried out using a lab-scale reactor system. The effects of operation conditions were investigated. Analyses on the gas, liquid and solid products were performed. Pyrolysis temperature turned out to be an important parameter determining the product yields. The optimum temperature was determined to be 500 °C for garlic stem and 480 °C for pepper stem at which the bio-oil yield was 39.6 wt.% and 45.8 wt.%, respectively. The bio-oil yield increased and the char yield decreased with increasing sample particle size.

The capability for the adsorption of Cu(II)-ion with mesoporous silica materials, such as MCM-41, SBA-15 and XPD-2412, after functionalizing with amine groups, such as aminopropyltriethoxysilane (APTES), N (β-aminoethyl) γ-aminopropylmethyl dimethoxysilane (AEAPMDMS) and N 1 -(3-(trimethoxysilyl)-propyl) diethylenetriamine (TMSPDETA), was investigated in this study. N 2 adsorption, XRD and elemental analysis methods were performed to gain an understanding of the structure and surface properties of the mesoporous silica materials. Of the absorbent materials, MCM-41, functionalized with APTES, showed the best activity for the adsorption of Cu(II)-ion. Compared with the mesoporous silica materials functionalized with APTES, those functionalized with AEAPMDMS and/or TMSPDETA showed lower adsorption capabilities, which may have been due to the locations of the amine groups. Most of the amine-organic domains were suggested should exist near the opening of channels or external surfaces. Furthermore, the rate of adsorption of Cu(II)-ions matched well with a pseudo-second-order kinetic model.

We study the propagation of a scalar, the trace of $h_{ij}$ in the deformed Ho\v{r}ava-Lifshitz gravity with coupling constant $\lambda$. It turns out that this scalar is not a propagating mode in the Minkowski spacetime background. In this work, we do not choose a gauge-fixing to identify the physical degrees of freedom and instead, make it possible by substituting the constraints into the quadratic Lagrangian., Comment: 17 pages, no figure, some points clarified

We study the entropy bound for local quantum field theory (LQFT) with generalized uncertainty principle. The generalized uncertainty principle provides naturally a UV cutoff to the LQFT as gravity effects. Imposing the non-gravitational collapse condition as the UV-IR relation, we find that the maximal entropy of a bosonic field is limited by the entropy bound $A^{3/4}$ rather than $A$ with $A$ the boundary area., Comment: 11 pages, 1figure, version to appear in PLB

The cosmological requirement of no domain wall gives a rather severe constraint to the number of fermion generations. We report on the results of our extensive search for grand unified models that can accomodate three or more generations of fermions and yet without suffering from the potentially catastrophic domain walls.