醇溶剂对提取松木中木质素影响的研究

主要考察了醇溶剂的种类、反应温度、醇质量分数、保温时间、酸的质量分数、液固比等六因素对醇类溶剂提取松木中木质素的影响,结果表明溶剂的种类及液固比对木质素产率影响较为显著,最佳工艺条件为反应温度170℃,液固比10∶1,保温时间120 min,醇的质量分数40%,酸用量0.1%,溶剂种类:乙二醇。另对产物进行紫外和红外光谱表征。     

固体酸SO_3/γ-Al_2O_3催化合成环己酮乙二醇缩酮工艺研究

以环己酮和乙二醇为原料,固体酸为催化剂,环己烷为带水剂,通过醇醛亲核加成反应合成了环己酮乙二醇缩酮。考察了催化剂用量、醛醇摩尔比、反应时间等因素对产品收率的影响。结果表明：SO3/γ-Al2O3固体酸具有良好的催化活性,较优工艺条件为：环己酮20.8 mL（0.20 mol）,n（环己酮）/n（乙二醇）=1︰1.2,催化剂0.5 g,环己烷10 mL,回流时间1.0 h,产物收率达96%以上。     

低密度聚乙烯生产过程中二次机及中冷器结垢分析

LDPE树脂工业化过程中二次压缩机及中冷器普遍存在聚乙烯结垢问题。熔融指数、密度测试结果显示,二次机和中冷器结垢物熔融指数及密度均分别为0.03g/10min,0.942g/cm3及0.12g/10min,0.936g/cm3,表明污垢并非来自高压循环气系统夹带。FT-IR测试结果,显示合格LDPE树脂和结垢物图谱在1364.69cm-1,1375.24cm-1中均出现叔丁基特征峰;在1721.42cm-1及1740cm-1均出现了酯类C=O伸缩振动吸收峰。红外图谱并未出现醚类碳-氧吸收峰,表明过氧化引发剂参与结垢物形成,氧气并未参与组合阀及中冷器污垢形成反应。本文证实了自由基来源、聚乙烯白色污垢的成因,对解决LDPE工业化过程中组合阀、中冷器结垢问题具有重要参考价值。     

崖城13-1气田南山终端天然气三甘醇脱水及再生系统2次故障的分析及解决方法

介绍崖城13-1气田南山终端天然气三甘醇脱水及再生系统工艺流程,并对该三甘醇脱水及再生系统的2次较大故障的现象、原因分析和排除方法进行详细描述。     

PEG/IPDI与PEG/TDI固化反应动力学研究

用二正丁胺滴定法对聚乙二醇(PEG)/甲苯二异氰酸酯(TDI)和PEG/异氟尔酮二异氰酸酯(IPDI)反应体系分别进行了研究,得到了相应体系在不同温度下的反应速率常数和活化能;并探讨了PEG分子量、固化剂的活性、燃烧催化剂和温度等因素对固化反应动力学参数和活化能的影响。结果表明:异氰酸酯和PEG反应为二级反应;PEG/IPDI和PEG/TDI体系固化反应的活化能分别为46.89kJ.mol-1和41.12kJ.mol-1;两体系的反应速率常数随着固化剂的活性和温度的增加而变大。不同活性的固化剂和燃烧催化剂虽影响两体系的固化反应速率常数,但不影响反应级数。     

Effect of molecular weight of oligomer on ionic diffusion in oligomer electrolytes and its implication for dye-sensitized solar cells

This study measures the diffusion coefficients of I⁻ and I₃⁻ in oligomer electrolytes as a function of the molecular weight of oligomers and investigates their effect on the performance of dye-sensitized solar cells (DSSCs). The high-diffusion coefficients of ions in an oligomer electrolyte with a lower molecular weight can help to promote the redox mechanism in DSSCs and thereby increase the short-circuit current density. They can also cause a decrease in the open-circuit voltage since a high-diffusion coefficient of I₃⁻ is capable of reducing the lifetime of electrons in TiO₂ electrodes. To offset these effects, N-methyl-benzimidazole is added to the oligomer electrolytes, thereby improving the open-circuit voltage and fill factor and, consequently, the overall energy-conversion efficiency, which increases to over 5%. A further test involving storage at a high temperature of 75 °C demonstrates that DSSCs employing the oligomer electrolytes show excellent thermal stability over 200 h.     

Improved H2 production from the APR of polyols in a microreactor utilizing Pt supported on a CeO2Al2O3 structured catalyst

In this research, the activity and selectivity of a platinum-based catalyst for H₂ production through aqueous phase reforming (APR) in a fixed-bed reactor (FBR) as well as, a structured catalyst microreactor (MR) were investigated. In this venue, first, an in-house designed MR was fabricated and the catalytic material was deposited on the channel walls of this steel made reactor. After verification of the stability of the coated layer, the prepared reactor was employed to investigate the APR reaction. In this regard, APR of the ethylene glycol and glycerol over Pt/Al₂O₃ and Pt/CeO₂Al₂O₃ catalyst were conducted in an MR and FBR. Obtained results demonstrated that employing Pt/CeO₂Al₂O₃ as a highly active catalyst in an FBR, slightly reduced the H₂ selectivity for the APR reaction of the ethylene glycol. Moreover, this effect appeared even more pronounced in reforming of glycerol. On the other hand, utilization of an MR for the APR of glycerol improved the H₂ selectivity due to the more active Pt/CeO₂Al₂O₃ catalyst, for this process. Comparison of the results revealed that the highly active catalyst alongside a reactor alleviating mass transfer limitations were two complementary factors leading to better performance of such chemical systems. Moreover, this research emphasized that obtained values of the APR conversion and H₂ selectivity in an MR coated with the Pt/CeO₂Al₂O₃ catalyst was superior to those obtained from an FBR. Ultimately, the best results obtained for the aforementioned catalytic species indicated that the APR of glycerol in a structured catalyst MR led to 75.3% conversion of glycerol and 92.4% selectivity to hydrogen production both of which were considerably better than results determined in an FBR.     

Enhanced saccharification of SO2 catalyzed steam-exploded corn stover by polyethylene glycol addition

Corn stover is a renewable, low cost and abundant feedstock in China. Its effective utilization is crucial for providing bioenergy, releasing environmental pollution and increasing farmers’ income. This aim of this study was to obtain the efficient saccharification of SO₂ catalyzed steam-exploded corn stover (SSECS) by polyethylene glycol (PEG) addition. According to the results, adding PEG6000 could lower the enzyme loading by 33.3%. With 20% solid loading, the highest glucose concentration of 102 g L⁻¹ and 91.3% saccharification yield were obtained using 30 CBU (g glucan)⁻¹ ??-glucosidase and 10 FPU (g glucan)⁻¹ cellulase in presence of PEG6000. In addition, protein and enzyme activities assays in the supernatants revealed that PEG could facilitate the desorption of enzyme protein from lignocellulose. These indicated that PEG addition not only can enhance enzymatic saccharification at high substrate concentration, but also can improve enzyme recycling by reducing the enzyme activity loss caused by adsorption during the hydrolysis.     

Psychrophilic hydrogen production from petrochemical wastewater via anaerobic sequencing batch reactor: techno-economic assessment and kinetic modelling

Independent hydrogen production from petrochemical wastewater containing mono-ethylene glycol (MEG) via anaerobic sequencing batch reactor (ASBR) was extensively assessed under psychrophilic conditions (15–25 °C). A lab-scale ASBR was operated at pH of 5.50, and different organic loading rates (OLR) of 1.00, 1.67, 2.67, and 4.00 gCOD/L/d. The hydrogen yield (HY) progressed from 134.32 ± 10.79 to 189.09 ± 22.35 mL/gMEG_initial at increasing OLR from 1.00 to 4.00 gCOD/L/d. The maximum hydrogen content of 47.44 ± 3.60% was achieved at OLR of 4.0 gCOD/L/d, while methane content remained low (17.76 ± 1.27% at OLR of 1.0 gCOD/L/d). Kinetic studies using four different mathematical models were conducted to describe the ASBR performance. Furthermore, two batch-mode experiments were performed to optimize the nitrogen supplementation as a nutrient (C/N ratio), and assess the impact of salinity (as gNaCl/L) on hydrogen production. HY substantially dropped from 62.77 ± 4.09 to 6.02 ± 0.39 mL/gMEG_initial when C/N ratio was increased from 28.5 to 114.0. Besides, the results revealed that salinity up to 10.0 gNaCl/L has a relatively low inhibitory impact on hydrogen production. Eventually, the cost/benefit analysis showed that environmental and energy recovery revenues from ASBR were optimized at OLR of 4.0 gCOD/L/d (payback period of 7.13 yrs).     

Poly(L-lysine)-poly(ethylene glycol) layers with different structure and their influence on silica suspension stability

The effects of the structure of di- and triblock copolymers of poly(L-lysine) – LYS with poly(ethylene glycol) – PEG as well as the length of nonionic fragment in the LYS-PEG macromolecule on the copolymer chains conformation in the adsorption layer formed on the colloidal silica (SiO2) surface were examined. Spectrophotometry and turbidimetry were applied for the determination of copolymer adsorbed amounts and stability coefficients of silica aqueous suspensions. The electrokinetic parameters such as solid surface charge density and zeta potential were also estimated. The adsorption of LYS-PEG was proved to be the highest at pH 10 whereas the lowest adsorption on the solid surface was found for the triblock copolymer with long fragments of LYS at the same pH value.