Chemical upcycling of PVC-containing plastic wastes by thermal degradation and catalysis in a chlorine-rich environment.

Chlorine (Cl)-containing chemicals, including hydrogen chloride, generated during thermal degradation of polyvinyl chloride (PVC) and corresponding mixture impede the chemical recycling of PVC-containing plastic wastes. While upgrading plastic-derived vapors, the presence of Cl-containing chemicals may deactivate the catalysts. Accordingly, herein, catalytic upgrading of pyrolysis vapor prepared from a mixture of PVC and polyolefins is performed using a fixed-bed reactor comprising zeolites. Among the H-forms of zeolites (namely, ZSM-5, Y, ß, and chabazite) used in this study, a higher yield of gas products composed of hydrocarbons with lower carbon numbers is obtained using H-ZSM-5, thus indicating further decomposition of the pyrolysis vapor to C1-C4 hydrocarbons on it. Although the formation of aromatic compounds is better on H-ZSM-5, product distributions can be adjusted by further modifying the acidic properties via the alteration of the Si/Al molar ratio, and maximum yields of C1-C4 compounds (60.8%) and olefins (64.7%) are achieved using a Si/Al molar ratio of 50. Additionally, metal ion exchange on H-ZSM-5 is conducted, and upgrading of PVC-containing waste-derived vapor to aromatic chemicals and small hydrocarbon molecules was successfully performed using Co-substituted H-ZSM-5. It reveals that the highest yield of gas products on 1.74 wt% cobalt (Co)-substituted H-ZSM-5 is acquired via the selection of an appropriate metal and metal ion concentration adjustment. Nevertheless, introduction of excess Co into the H-ZSM-5 surface decreases the cracking activity, thereby implying that highly distributed Co is required to achieve excellent cracking activity. The addition of Co also adjusted the acid types of H-ZSM-5, and more Lewis acid sites compared to Brønsted acid sites selectively produced olefins and naphthenes over paraffins and aromatics. The proposed approach can be a feasible process to produce valuable petroleum-replacing chemicals from Cl-containing mixed plastic wastes, contributing to the closed loops for upcycling plastic wastes.

Stabilization of acid-rich bio-oil by catalytic mild hydrotreating.

Although liquid products derived from the pyrolysis of biomass are promising for the production of petroleum-like hydrocarbon fuels, the catalytic burden of hydrodeoxygenation must be reduced to achieve feasible upgrading processes. Herein, mild hydrotreating of an acid-rich biomass pyrolysis oil (bio-oil) with an unusually high total acid number (588 mg KOH/g bio-oil) was performed to stabilize the low-quality bio-oil. Ru-added TiO2-supported transition metal catalysts stabilized the bio-oil by reducing its acidity more compared to what could be achieved by Ru-free catalysts; this process also leads to lower loss of organic compounds compared to when using a Ru/TiO2 catalyst. Based on the performance of transition metal catalysts, including Ni, Co, and Cu, supported on TiO2, tungstate-zirconia, or SiO2, supported bimetallic catalysts were prepared by adding Ru to the TiO2-supported metal catalysts. The bimetallic catalysts Ru/Ni/TiO2 and Ru/Co/TiO2 exhibited good decarboxylation activity for the removal of carboxylic acids and a higher yield of organic compounds compared to that provided by Ru, which can be deemed appropriate for feedstocks when hydrodeoxygenation needs to suppress the loss of organic reactants. Using these catalysts, the carboxylic acid concentration was reduced to 319-323 mg KOH/g bio-oil with organic yields of 62-63 wt% at reaction temperatures 150-170 °C lower than the temperature required for direct conversion of carboxylic acids to alcohols or deoxygenates. The improved catalytic hydrotreating activity of Ru-added transition metals can be attributed to the high acid site densities of these catalysts along with their improved hydrogenation activities.

Improved catalytic depolymerization of lignin waste using carbohydrate derivatives.

CARBOHYDRATE-: or sugar-derived compounds were used as environmentally friendly additives for the depolymerization of Kraft lignin waste and organosolv lignin prepared from Miscanthus giganteus. The yields of the aromatic monomers obtained from Kraft lignin increased from 5.1 to 49.2% with the addition of mannitol, while those obtained from organosolv lignin increased from 44.4 to 83.0% with the addition of sucrose. This improved lignin depolymerization was also confirmed by gel permeation chromatography and nuclear magnetic resonance spectroscopy. The above results clearly indicate the beneficial effects of carbohydrate derivatives on the lignin depolymersization process, more specifically, suggesting that the presence of carbohydrates improve the lignin depolymerization of lignocellulose, as observed for the raw lignocellulose feed.

SiO2@MnO x @Na2WO4@SiO2 core-shell-derived catalyst for oxidative coupling of methane.

SiO2@MnO x @Na2WO4@SiO2 core-shell catalysts were prepared and their fabrication was confirmed using transmission electron microscopy. The formation of Mn-based nanosheets on the silica spheres is important for the deposition of nanoscopic Na2WO4. The SiO2@MnO x @Na2WO4@SiO2 core-shell catalysts were used for the oxidative coupling of methane at a temperature of 700-800 °C at which the nanostructures were completely destroyed. Although the core-shell structures did not survive the high-temperature oxidative coupling of methane, the selective production of olefins and paraffins can be attributed to highly dispersed Na2WO4 derived from confined core-shell structures.

Study on the unsteady state oxidative coupling of methane: effects of oxygen species from O2, surface lattice oxygen, and CO2 on the C2+ selectivity.

This study examined the effects of oxygen species on the unsteady-state oxidative coupling of methane (OCM) using a lengthy catalyst bed of Na2WO4/Mn/SiO2. The reaction conditions, including the methane-to-oxygen ratio, ratio of feed gas dilution by N2, quantity of catalyst, and feed flow rate were adjusted for the continuous flow fixed bed reaction system. While the O2 gas initiated methyl radical formation from methane, the surface lattice oxygen atoms improved the dehydrogenation of paraffins to olefins without significant activation of methane. The addition of CO2 as a mild oxidizing agent was also tested and slightly improved OCM selectivity with slightly lower methane conversion were observed.

Chronic hepatitis B infection and non-hepatocellular cancers: A hospital registry-based, case-control study.

BACKGROUND: Prior epidemiological evidences suggest that hepatitis B virus (HBV) infection is linked to cancers other than hepatocellular carcinoma. This prospective hospital registry-based case-control study aimed to investigate the sero-epidemiological association between chronic HBV infection and various types of cancer. METHODS: 95,034 patients with first-diagnosed non-hepatocellular malignancy in a tertiary hospital between 2007 and 2014; and 118,891 non-cancer individuals as controls from a health promotion center were included. Cases and controls were compared for HBV surface antigen (HBsAg) positivity by conditional regression with adjustment for age, hypertension, diabetes, body mass index, alcohol consumption, smoking status and cholesterol level in both genders. RESULTS: An analysis of matched data indicated significant associations of HBV infection with lymphoma (adjusted odds ratio[AOR] 1.53 [95% CI 1.12-2.09] in men and 3.04 [1.92-4.82] in women) and biliary cancer (2.59[1.98-3.39] in men and 1.71[1.16-2.51] in women). Cervical (1.49[1.11-2.00]), uterine (1.69[1.09-2.61]), breast (1.16[1.02-1.32]), thyroid (1.49[1.28-1.74]), and lung cancers (1.79[1.32-2.44]) in women; and skin cancer (5.33[1.55-18.30]) in men were also significantly related to HBV infection. CONCLUSIONS: Chronic HBV infection is associated with several malignant disorders including lymphoma, and biliary, cervical, uterine, breast, thyroid, lung, and skin cancers. Our findings may offer additional insights into the development of these neoplasms and may suggest the need to consider HBV screening in cancer patients and cancer surveillance in HBV-infected subjects.

Efficacy and safety of entecavir versus lamivudine over 5 years of treatment: A randomized controlled trial in Korean patients with hepatitis B e antigen-negative chronic hepatitis B.

BACKGROUND/AIMS: Long-term data on antiviral therapy in Korean patients with hepatitis B e antigen (HBeAg)-negative chronic hepatitis B (CHB) are limited. This study evaluated the efficacy and safety of entecavir (ETV) and lamivudine (LAM) over 240 weeks. METHODS: Treatment-naive patients with HBeAg-negative CHB were randomized to receive ETV 0.5 mg/day or LAM 100 mg/day during the 96 week double-blind phase, followed by open-label treatment through week 240. The primary endpoint was the proportion of patients with virologic response (VR; hepatitis B virus [HBV] DNA<300 copies/mL) at week 24. Secondary objectives included alanine aminotransferase (ALT) normalization and emergence of ETV resistance (week 96), VR and log reduction in HBV DNA levels (week 240), and safety evaluation. RESULTS: In total, 120 patients (>16 years old) were included (ETV, n=56; LAM, n=64). Baseline characteristics were comparable between the two groups. A significantly higher proportion of ETV-treated patients achieved VR compared to LAM at week 24 (92.9% vs. 67.2%, P=0.0006), week 96 (94.6% vs. 48.4%, P<0.0001), and week 240 (95.0% vs. 47.6%, P<0.0001). At week 96, ALT normalization was observed in 87.5% and 51.6% of ETV and LAM patients, respectively (P<0.0001). Virologic breakthrough occurred in one patient (1.8%) receiving ETV and 26 patients (42.6%) receiving LAM (P<0.0001) up to week 96. Emergence of resistance to ETV was not detected. The incidence of serious adverse events was low and unrelated to the study medications. CONCLUSIONS: Long-term ETV treatment was superior to LAM, with a significantly higher proportion of patients achieving VR. Both treatments were well tolerated.

Effective depolymerization of concentrated acid hydrolysis lignin using a carbon-supported ruthenium catalyst in ethanol/formic acid media.

Lignin isolated by two-step concentrated acid hydrolysis of empty fruit bunch (EFB) was effectively depolymerized into a high-quality bio-oil using formic acid (FA) as an in-situ hydrogen source and Ru/C as a catalyst in supercritical ethanol. A bio-oil yield of 66.3wt% with an average molecular weight of 822g/mol and an aromatic monomer content of 6.1wt% was achieved at 350°C and a FA-to-lignin mass ratio of 3 after a reaction time of 60min. The combination of Ru/C and FA also resulted in a significant reduction in the oxygen content of the bio-oil by ∼60% and a corresponding increase in the higher heating value (HHV) to 32.7MJ/kg due to the enhanced hydrodeoxygenation activity. An examination of the FA decomposition characteristics revealed that Ru/C provides a greater increase in the rate of hydrogen production from FA, explaining the efficient depolymerization of lignin in a combined system.

Sclerosing encapsulating peritonitis in a long-term propranolol user.

Sclerosing encapsulating peritonitis (SEP) is a rare cause of bowel obstruction that is characterized by the encasement of the small bowel by a thick, whitish, and fibrous membrane. The pathophysiology of SEP is poorly understood and preoperative diagnosis is difficult. Previous reports suggest that SEP may be linked to the chronic use of ß-adrenergic blockers. A 46-year-old man with liver cirrhosis and end-stage renal disease on hemodialysis presented with recurrent abdominal pain and borborygmi. He had been taking propranolol to prevent bleeding from gastroesophageal varices for the past 15 years. Abdominal computed tomography showed ileal loops encapsulated by soft tissue with dilatation of the proximal small bowel on the right side of the abdomen. Barium follow-through showed conglomerated distal ileal loops with a cauliflower-like appearance. Explorative laparotomy revealed a thick, fibrous, whitish capsule encapsulating the ileal loops. The covering membrane was dissected and excised, resulting in an improvement in symptoms after surgery. Accordingly, a final diagnosis of SEP was made. Due to the lack of other apparent causes for SEP, we conclude that in this case, the long-term use of propranolol may be associated with the development of SEP.

Catalytic Reforming of Lignin-Derived Bio-Oil Over a Nanoporous Molecular Sieve Silicoaluminophosphate-11.

Catalytic pyrolysis of lignin, a major constituent of biomass, was performed. A nanoporous molecular sieve silicoaluminophosphate-11 (SAPO-11) was selected as catalyst. Thermogravimetric analysis showed that 500 degrees C was the optimal pyrolysis temperature. Pyrolyzer-gas chromatography/mass spectroscopy was used to investigate the pyrolysis product distribution. Production of phenolics, the dominant product from the pyrolysis of lignin, was promoted by the increase in the catalyst dose. In particular, low-molecular-mass phenolics were produced more over SAPO-11, while high-molecular-mass phenolics and double-bond-containing phenolics were produced less. The fraction of aromatic compounds, including benzene, toluene, xylene, and ethylbenzene, was also increased by catalytic reforming. The catalytic effects were more pronounced when the catalyst/biomass ratio was increased. The enhanced production of aromatic compounds by an acidic catalyst obtained in this study is in good agreement with the results of previous studies.

Highly Dispersed Pt Nanoparticles for the Production of Aromatic Hydrocarbons by the Catalytic Degrading of Alkali Lignin.

Aromatic hydrocarbons were produced from lignin, a complex natural amorphous polymer commonly regarded as by-product of the pulping process and from biofuel production. The catalytic decomposition of lignin using supported Pt catalysts was performed to produce small molecule hydrocarbons. Aromatic small-molecule hydrocarbon products were identified and quantified using GC/MS and GC-FID, which demonstrated that 27.6% of aromatic hydrocarbons were obtained from the activated carbon-supported Pt (Pt/AC) catalyst which had the highest Pt surface area.

Catalytic Depolymerization of Alkali Lignin Using Supported Pt Nanoparticle Catalysts.

Alkali lignin, a byproduct of the pulping process, was depolymerized using Pt nanoparticle catalysts. A depolymerized lignin with a lower molecular weight was obtained and characterized with GPC and NMR. 31P-NMR using OH-sensitive probing molecules showed the formation of guaiacyl OHs during the reaction, indicating the cleavage of guaiacyl ether bonds.

Comprehensive outcomes of on- and off-antiviral prophylaxis in hepatitis B patients undergoing cancer chemotherapy: A competing risks analysis.

Although antiviral prophylaxis is essential in hepatitis B patients in the context of cancer chemotherapy, there is little evidence-based consensus regarding the appropriate prevention strategy depending on the underlying type of cancer and viral status. This retrospective study included a comprehensive cohort of 302 hepatitis B surface antigen-positive patients with various cancers undergoing chemotherapy and antiviral prophylaxis. The rates of hepatitis B virus (HBV) reactivation during antiviral therapy (>1 log10 IU/mL increase or positive conversion of serum HBV DNA) and relapse when off antivirals ([re]appearance of HBV DNA >2,000 IU/ml with related alanine aminotransferase elevation) were evaluated, together with the associated risk factors, in a competing risks analysis where cancer death was considered as the competing event. During antiviral prophylaxis, HBV was reactivated in six patients (1.9%), who had leukemia (n = 4) or lymphoma (n = 2) and were treated with lamivudine (n = 4) or entecavir (n = 2). The incidence rate of HBV relapse in 127 off-prophylaxis patients was 21.3% during a median post-antiviral period of 11.7 months. Lymphoma, pre-prophylactic HBV DNA ≥2,000 IU/ml, and age ≥50 years were independent predictors of off-treatment HBV relapse (adjusted hazard ratios 5.25, 3.07, and 0.34, respectively; Ps < 0.05). Antiviral and anticancer drugs, duration of consolidation on antiviral prophylaxis, and HBeAg positivity were not independent predictors. In conclusion, hepatitis B flare-ups are not rare in patients receiving cancer chemotherapy during and after anti-HBV prophylaxis, even when potent antivirals are used. Patients with hematopoietic or lymphoid neoplasms or high viral burdens should receive prolonged and powerful HBV prophylaxis. J. Med. Virol. 88:1576-1586, 2016. © 2016 Wiley Periodicals, Inc.

Hydro- and solvothermolysis of kraft lignin for maximizing production of monomeric aromatic chemicals.

The hydro-/solvothermolysis of kraft lignin using water and ethanol as a solvent were investigated in this study. The effect of the water-to-ethanol ratio on the yields of monomeric aromatic chemicals (MACs) and the kinetic behavior of MACs was studied in a series of batch experiments. The yields of MACs other than catechol increased as the ratio of ethanol increased, and the content of the total MACs in bio-crude oil (BCO) reached 35% when the ratio of ethanol was 100% at a reaction temperature of 300 °C. The formation of phenol, guaiacol, and alkylguaiacols was enhanced in ethanol, while the formation of catechol was dominant in water. The formation of more substituted MACs such as vanillin, acetoguaiacone, and homovanillic acid was not affected by the solvent. The role of reaction parameters on the yields of MACs was elucidated, and the main reaction pathways in water and in ethanol were proposed.

No association between the IL28B SNP and response to peginterferon plus ribavirin combination treatment in Korean chronic hepatitis C patients.

BACKGROUND/AIMS: There are few available data regarding the association between the single nucleotide polymorphisms (SNPs) of the gene encoding interleukin 28B (IL28B) and a sustained virologic response (SVR) to peginterferon (PEG-IFN) plus ribavirin (RBV) therapy in Korean chronic hepatitis C patients. METHODS: This was a retrospective cohort study of 156 patients with chronic hepatitis C virus (HCV) infection who received combination treatment of PEG-IFN plus RBV. Blood samples from these patients were analyzed to identify the IL28B SNPs at rs12979860, rs12980275, rs8099917, and rs8103142. Association analyses were performed to evaluate the relationships between each IL28B SNP and SVRs. RESULTS: Seventy six patients with HCV genotype 1 and 80 with genotype non-1 were enrolled. The frequencies of rs12979860 CC and CT genotypes were 90.4% and 9.6%, respectively; those of rs12980275 AA and AG genotypes were 87.2% and 12.8%, respectively; those of rs8099917 TT and TG genotypes were 92.3% and 7.7%, respectively; and those of rs8103142 TT and CT genotypes were 90.4% and 9.6%, respectively. Among the patients with HCV genotype 1, the SVR rates were 69.7% and 80.0% for rs12979860 CC and CT, respectively (P=0.71). Among the HCV genotype non-1 patients, SVR rates were 88.0% and 100% for rs12979860 CC and CT (P=1.00), respectively. CONCLUSIONS: Genotypes of the IL28B SNP that are known to be favorable were present in most of the Korean patients with chronic hepatitis C in this study. Moreover, the IL28B SNP did not influence the SVR rate in either the HCV genotype 1 or non-1 patients. Therefore, IL28B SNP analysis might be not useful for the initial assessment, prediction of treatment outcomes, or treatment decision-making of Korean chronic hepatitis C patients.

Rescue therapy with adefovir in decompensated liver cirrhosis patients with lamivudine-resistant hepatitis B virus.

BACKGROUND/AIMS: Adefovir dipivoxil (ADV) is a nucleotide analogue that is effective against lamivudine-resistant hepatitis B virus (HBV). The aim of this study was to determine the long-term clinical outcomes after ADV rescue therapy in decompensated patients infected with lamivudine-resistant HBV. METHODS: In total, 128 patients with a decompensated state and lamivudine-resistant HBV were treated with ADV at a dosage of 10 mg/day for a median of 33 months in this multicenter cohort study. RESULTS: Following ADV treatment, 86 (72.3%) of 119 patients experienced a decrease in Child-Pugh score of at least 2 points, and the overall end-stage liver disease score decreased from 16±5 to 14±10 (mean ± SD, P<0.001) during the follow-up period. With ADV treatment, 67 patients (56.3%) had undetectable serum HBV DNA (detection limit, 0.5 pg/mL). Virologic breakthrough occurred in 38 patients (36.1%) and 9 patients had a suboptimal ADV response. The overall survival rate was 89.9% (107/119), and a suboptimal response to ADV treatment was associated with both no improvement in Child-Pugh score (≥2 points; P=0.001) and high mortality following ADV rescue therapy (P=0.012). CONCLUSIONS: Three years of ADV treatment was effective and safe in decompensated patients with lamivudine-resistant HBV.

Comparative study on two-step concentrated acid hydrolysis for the extraction of sugars from lignocellulosic biomass.

Among all the feasible thermochemical conversion processes, concentrated acid hydrolysis has been applied to break the crystalline structure of cellulose efficiently and scale up for mass production as lignocellulosic biomass fractionation process. Process conditions are optimized by investigating the effect of decrystallization sulfuric acid concentration (65-80 wt%), hydrolysis temperature (80°C and 100°C), hydrolysis reaction time (during two hours), and biomass species (oak wood, pine wood, and empty fruit bunch (EFB) of palm oil) toward sugar recovery. At the optimum process condition, 78-96% sugars out of theoretically extractable sugars have been fractionated by concentrated sulfuric acid hydrolysis of the three different biomass species with 87-90 g/L sugar concentration in the hydrolyzate and highest recalcitrance of pine (softwood) was determined by the correlation of crystallinity index and sugar yield considering reaction severity.

Catalytic upgrading of xylan over mesoporous Y catalyst.

In-situ catalytic cracking of xylan, a model compound of hemicellulose, was carried out using pyrolysis-gas chromatography/mass spectrometry over mesoporous Y for the first time. Experiments were conducted at three different temperatures, 400 degrees C, 450 degrees C, and 500 degrees C, to investigate the effect of reaction temperature. Three different biomass-to-catalyst ratios, 1:1, 1:2, and 1:3, were tested at 500 degrees C to examine the effect of catalyst dose. In addition, the catalytic activity of mesoporous Y was compared with that of Al-MCM-41. The catalysts used were characterized by N2 adsorption-desorption, temperature programmed desorption of NH3, and X-ray diffraction. The main pyrolysis products of xylan were acids, hydrocarbons, phenolics, oxygenates, aromatics, and polycyclic aromatic hydrocarbons. Mesoporous Y, which has acid sites with larger quantity and stronger acidity than those of Al-MCM-41, was shown to enhance the quality of bio-oil to a larger extent, producing a larger quantity of high-value-added products, such as aromatics and furans.

Application of mesoporous Al-MCM-48 material to the conversion of lignin.

Al-MCM-48 was applied to the catalytic pyrolysis of lignin for the first time. The pyrolysis reaction and in-situ product were analyzed by pyrolysis gas chromatography/mass spectrometry. The main products of the non-catalytic pyrolysis of lignin were phenols. The use of Al-MCM-48 increased the production of light phenols considerably. The yields of high-value-added compounds, such as hydrocarbons and aromatics, were also increased by catalytic upgrading. Al-MCM-48 is believed to promote cracking, aromatization and deoxygenation, such as decarbonylation. On the other hand, Si-MCM-48, which has no acid sites, showed lower deoxygenation efficiency than Al-MCM-48. Al-MCM-48 could be regenerated by calcining in air.