Catalytic pyrolysis of corn straw for deoxygenation of bio-oil with different types of catalysts

Wenkai Zhang,Ze Wang,Tengze Ge,Cuiguang Yang,Wenli Song,Songgeng Li,Rui Ma 한국화학공학회 2022 Korean Journal of Chemical Engineering Vol.39 No.5

Corn straw can be converted to bio-oil through pyrolysis. However, the application of bio-oil is severelyrestricted due to the high content of oxygen. Catalytic pyrolysis is an available way for deoxygenation of bio-oil, and thedeoxygenation reactions are strongly dependent on the type of catalyst. Whereas, the correlation between the deoxygenatedproducts and the catalyst types is still far from clear. In this work, the migration of O in the pyrolysis processwas investigated, and eight catalysts were screened for deoxygenation of bio-oil, with a lab-scale fixed-bed reactor. Theresults showed that with the increase of pyrolysis temperature, the content of O in bio-oil decreased below 400 oC andthen became stable and finally increased rapidly after 550 oC, indicating that the range of 400-550 oC was the propertemperature for deoxygenation. Eight catalysts (ZSM-5, SAPO-34, ZnO, MgO, -Al2O3, -Al2O3, acidified--Al2O3 andacidified--Al2O3) were tested, and it was found that a higher alkalinity of catalyst was favorable for decarboxylation ofbio-oil with more produced CO2, while a higher acidity was promoted the decrease of alcohols and carbonyls withmore generation of H2O and/or CO. MgO was judged as the optimal catalyst for deoxygenation of bio-oil. The qualityof bio-oil under the catalysis of MgO was best, with higher H/C and lower O/C.

Effect of Oxygen Functionalities of Graphene Oxide on Polymerization and Thermal Properties of Reactive Benzoxazine Nanocomposites

Wenkai Zhang,Yanshan Zhan,Xiuxiu Gao,Runming Li,Weiwei Zhu,Hao Xu,Baoying Liu,Xiaomin Fang,Yuanqing Xu,Tao Ding 한국고분자학회 2018 Macromolecular Research Vol.26 No.1

Herein, we report the effect of oxygen functionalities of graphene oxide on thermal activated polymerization and thermal properties of reactive benzoxazine nanocomposites. The numbers of oxygen moieties of graphene oxide (GO) are controlled by hydrothermal reduction. The polymerization behavior of benzoxazine monomer (BA-a) is studied by Fourier transform infrared spectroscopy, differential scanning calorimetry and rheological analysis. It is hypothesized that the GO not only exhibits accelerated effect on the polymerization of the BA-a, but also the oxygen moieties such as carboxyl groups of GO interact with the benzoxazine polymers, leading to several orders of magnitude increase in the chemoviscosity and modulus of composite system. Thermal conductivity of poly(BA-a)/GO composite increases from an initial value of ∼0.27 W/mK to 0.47 W/mK as the loading increases from 1 wt% to 6 wt% (enhancement factor up to 176%). Moreover, the nanocomposites display enhanced initial decomposition temperature and char yields as the degree of GO reduction increases.

Erratum: Optimal Structure Design and Performance Analysis of Multiphase Twin screw Pump for Wet Gas Compression

Xuejing Zhang,Junhu Yang,Wenkai Bei,Wei Han,Canyang Chen,Le Yang 한국유체기계학회 2021 International journal of fluid machinery and syste Vol.14 No.3

Optimal Structure Design and Performance Analysis of Multiphase Twin-screw Pump for Wet Gas Compression

Xuejing Zhang,Junhu Yang,Wenkai Bei,Wei Han,Canyang Chen,Le Yang 한국유체기계학회 2021 International journal of fluid machinery and syste Vol.14 No.2

The efficiency of multiphase twin-screw pump decreases sharply under wet gas conditions (GVF>95%) with severe vibration and thermal problems. Based on the design characteristics of twin-screw pump and screw compressor, a design method of multigradient variable pitch decompression screw pump is to address these problems in this paper. This method keeps the cross section profiles of screw pump unchanged,only changes the pitch of screw. According to the design concept of decompression of screw compressor, the screw rotor is divided into three regions from the inlet to the outlet. The pitch of screw and thread width in these regions are designed separately to increase the volumetric efficiency of the screw pump and reduce the vibration. The effective clearance leakage model of twin-screw pump is simplified and modified. Considering two-phase back flow and combining mechanical model with thermodynamic model, the flow capacity, volumetric efficiency, pressure, and temperature distribution of new and conventional screw pumps are predicted by non-isothermal compression model. The calculations show that the design scheme of multi-gradient variable-pitch decompression screw pump can solve the volumetric efficiency and vibration problems under wet gas conditions fundamentally and can significantly reduce the power consumption of screw pump. However, the problem of temperature rise of screw pump still exists. Cooling system for the screw pump should be designed to continuously cool the screw pump.

Reservoir bank slope stability prediction model based on BP neural network

Guoqiang Zhang,Wenkai Feng,Mingtang Wu,Hai Shao,Feng Ma 국제구조공학회 2021 Steel and Composite Structures, An International J Vol.41 No.2

Safety monitoring and stability analysis of high slopes are essential for construction of concrete dam in precipitous gorges or mountainous areas. The estimate of slope stability is a difficult engineering shortcoming with a number of variables. Thereafter, a hybrid model of Support Vector Regression (SVR) and Teaching–learning-based optimization technique (TLBO) is proposed to develop the predicting function. TLBO was used in obtaining the best SRV factors to improve the prediction accuracy. Few essential factors, such as the installation height of instruments, classification of rock masses, modulus of elasticity, the complete measuring time cycle, the excavation height of slope, the start measuring time, and the actual excavation height after measurement are considered as the input parameter, but the slope displacement is regarded as output. The outcomes showed SRV-TLBO a reliable hybrid accurate prediction of slope stability, then it was effectively used to the left abutment slope of Jinping I hydropower station located in Yalongjiang concrete dam reservoir as a novel method for this purpose.

H2 Metabolism revealed by metagenomic analysis of subglacial sediment from East Antarctica

Zhifeng Yang,Yu Zhang,Yongxin Lv,Wenkai Yan,Xiang Xiao,Bo Sun,Hongmei Ma 한국미생물학회 2019 The journal of microbiology Vol.57 No.12

Subglacial ecosystems harbor diverse chemoautotrophic microbial communities in areas with limited organic carbon, and lithological H2 produced during glacial erosion has been considered an important energy source in these ecosystems. To verify the H2-utilizing potential there and to identify the related energy-converting metabolic mechanisms of these communities, we performed metagenomic analysis on subglacial sediment samples from East Antarctica with and without H2 supplementation. Genes coding for several [NiFe]- hydrogenases were identified in raw sediment and were enriched after H2 incubation. All genes in the dissimilatory nitrate reduction and denitrification pathways were detected in the subglacial community, and the genes coding for these pathways became enriched after H2 was supplied. Similarly, genes transcribing key enzymes in the Calvin cycle were detected in raw sediment and were also enriched. Moreover, key genes involved in H2 oxidization, nitrate reduction, oxidative phosphorylation, and the Calvin cycle were identified within one metagenome-assembled genome belonging to a Polaromonas sp. As suggested by our results, the microbial community in the subglacial environment we investigated consisted of chemoautotrophic populations supported by H2 oxidation. These results further confirm the importance of H2 in the cryosphere.

Effect of plant secondary metabolites on common cutworm, Spodoptera litura (Lepidoptera: Noctuidae)

Qi Su,Zhixiong ZHOU,Jianmin ZHANG,Caihua SHI,Guohui ZHANG,Zhenyu JIN,Wenkai WANG,Chuanren LI 한국곤충학회 2018 Entomological Research Vol.48 No.1

The effect of various flavonoids, lectins and phenyl β‐D‐glucoside on larval survival, weights and the activities of digestive (total serine protease and trypsin) and detoxifying (esterase and glutathione‐S‐transferase) enzymes of Spodoptera litura larvae at 7 days after treatment was studied through diet incorporation assay. Flavonoids (rutin, chlorogenic acid, quinic acid, caffeic acid, naringenin, quercitin, kaempferol, myricetin, catechin, and ferulic acid) were incorporated in artificial diet at 100, 500 and 1000 ppm, lectins: groundnut leaf lectin (GLL), concavalin A (ConA) and phenyl β‐D‐glucoside at 1, 2 and 5 μg/mL. Flavonoids such as rutin, quercitin and kaempferol at 1000 ppm were more toxic to S. litura larvae than quinic acid, caffeic acid, naringenin, myricetin, catechin, and ferulic acid. Larval growth and development were significantly reduced in S. litura larvae fed on a diet with GLL and ConA at 5 μg/mL compared to the larvae fed at 2 and 1 μg/mL concentrations. The larvae fed on flavonoid‐treated diets showed significant reduction in serine protease, trypsin and esterase activities. The flavonoids such as rutin, chlorogenic acid, quinic acid, naringenin, quercitin, kaempferol and myricetin, and lectins, GLL and ConA can be utilized in insect control programs.

Efficiency of gerAa, tupA and ca transformation in Bacillus subtilis for self-healing of concrete cracks

Hanxing He,Gefei Li,Jiantao Zhang,Jinlong Zhang,Mingyue Luo,Wenkai Hu,Yamin Lin,Ziyu Deng,Zhicheng Liu,Weizhao Chen,Xu Deng 한양대학교 세라믹연구소 2019 Journal of Ceramic Processing Research Vol.20 No.5

A genetic approach was proposed to modify the characteristics of Bacillus subtilis strain WB800 (B. subtilis WB800) for selfhealing of concrete cracks. Three genes, namely gerAa which encodes germination receptors activated by L-alanine, tupA which is responsible for the synthesis of teichuronopeptide, and ca which encodes carbonic anhydrase (CA) catalyzing the synthesis of carbonate ion, were separately transformed into WB800. To protect bacterial cells from being squeezed, microspheres were produced with microcrystal cellulose (MCC) before the introduction of bacteria into the specimens. The results showed that the modified B. subtilis expressing GerA achieved 39.9% of germination ratio compared to 17% by the original host cells. With the transformation of tupA, the modified strain demonstrated higher resistance to alkaline environments, tolerating pH as high as 11, while the original strain only tolerated pH 9. The modified strain expressing CA induced more calcium carbonate than the original cells. Energy dispersive spectroscopy (EDS) identified the produced precipitate to be calcite (CaCO3). Moreover, a mathematical model was developed to optimize the influential factors of calcium precipitation process. Finally, based on the above results, an effective self-healing of concrete crack was achieved. This study may provide a promising strategy to improve the efficiency of bacterial self-healing of concrete cracks.