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561.
Investigation of catalytic degradation of high-density polyethylene by hydrocarbon group type analysis 总被引:1,自引:0,他引:1
Young-Hwa Seo Kyong-Hwan Lee Dae-Hyun Shin 《Journal of Analytical and Applied Pyrolysis》2003,70(2):6061-398
Catalytic degradation of waste high-density polyethylene (HDPE) to hydrocarbons by ZSM-5, zeolite-Y, mordenite and amorphous silica–alumina were carried out in a batch reactor to investigate the cracking efficiency of catalysts by analyzing the oily products including paraffins, olefins, naphthenes and aromatics with gas chromatography/mass spectrometry (GC/MS). Catalytic degradation of HDPE with zeolite-Y, mordenite and amorphous silica–alumina yielded 71–82 wt.% oil fraction, which mostly consisted of C6–C12 hydrocarbons, whereas ZSM-5 yielded much lower 35% oil fraction, which mostly consisted of C6–C12 hydrocarbons. Both all zeolites and silica–alumina increased olefin content in oil products, and ZSM-5 and zeolite-Y particularly enhanced the formation of aromatics and branched hydrocarbons. ZSM-5 among zeolites showed the greatest catalytic activity on cracking waste HDPE to light hydrocarbons, whereas mordenite produced the greatest amount of coke. Amorphous silica–alumina also showed a great activity on cracking HDPE to lighter olefins in high yield, but no activity on aromatic formation. 相似文献
562.
本文以雪莲果为碳源,采用热解法制备碳材料(C),以硝酸钴、四硼酸钠和碳材料为原料,通过热解法合成硼掺杂四氧化三钴/碳(B-Co3O4/C)复合纳米材料。运用XRD、FTIR、SEM、XPS等手段对其结构、形貌和组成进行表征。利用线性扫描(LSV)和Tafel曲线等电化学测试方法研究了B-Co3O4/C复合纳米材料的电催化析氧反应(OER)性能。结果表明,该材料具有较好的电催化OER活性。在1.0mol/L的KOH电解液和10mA·cm-2的电流密度下,B-Co3O4/C复合纳米材料的过电位为293mV,Tafel斜率为45.0mV·dec-1。在10mA·cm-2电流密度下连续测试10h, B-Co3O4/C的电位变化不大,通过法拉第效率测试该催化剂的产氧效率为94%,说明硼原子的掺入改变了B-Co3O4... 相似文献
563.
564.
Although metal-organic frameworks(MOFs) have been widely reported as precursors for obtaining various porous materials in recent years, the limited MOF types and monofunctional active site of MOF-based catalysts remain to be hard to crack. Herein, bimetallic MOFs, MCo-ZIFs stabilized by graphitized carbon nitride(g-C3N4) and their pyrolytic MxCo3O4/g-C3N4 hybrids(M=Zn, Cu, Fe, Ni) have been designedly synthesized. The obtained MxCo3O4/g-C3N4 hybrids display synergistic photothermal effect from both MxCo3O4 and g-C3N4 under visible light irradiation. Significantly, the solution temperature can be heated from room temperature(20℃) to 66℃ after 40 min irradiation. Therefore, the catalytic activity of MxCo3O4/g-C3N4 exceeds those of most reported catalysts under mild reaction conditions. The optimal ZnxCo3O4/g-C3N4 catalyst realizes 96% conversion and 75% selectivity toward styrene oxide within 20 min. Incredibly, the CuxCo3O4/g-C3N4 could achieve up to 89% selectivity toward styrene oxide. To our knowledge, this is the first report about the novel photothermal effect of ZIFs-derived metal oxides. 相似文献
565.
《高分子科学杂志,A辑:纯化学与应用化学》2013,50(6):713-725
Abstract Pyrolysis of electrochemically prepared BF4 ? doped polythiophene (PTh) by direct insertion probe and Currie point pyrolysis gas chromatography mass spectrometry techniques indicated that thermal decomposition of PTh occurs in two steps. In accordance with literature results, the first step is assigned to the loss of the dopant, and the second step to the degradation of the polymer backbone producing segments of various conjugation lengths. At elevated temperatures, detection of products such as H2S and C2H2 indicating cleavage of the thiophene (Th) ring was associated with a network structure. For the dedoped samples, a significant increase in the relative intensities of the peaks characteristic to the counter ion of the dopant, N(C4H9)4 + pointed out the inward diffusion of (C4H9)4N+ during the dedoping process. 相似文献
566.
Matthew A. Oehlschlaeger Ronald K. Hanson 《Proceedings of the Combustion Institute》2007,31(1):211-219
The two-channel thermal decomposition of toluene, C6H5CH3 → C6H5CH2 + H (1) and C6H5CH3 → C6H5 + CH3 (2), was investigated in shock tube experiments over the temperature range of 1400-1780 K at a pressure of 1.5 (±0.1) bar. Rate coefficients for reactions (1) and (2) were determined by monitoring benzyl radical (C6H5CH2) absorption at 266 nm during the decomposition of toluene diluted in argon and modeling the temporal behavior of the benzyl concentration with a kinetic model. The first-order rate coefficients determined at a pressure of 1.5 bar are expressed by k1(T) = 2.09 × 1015 exp (−87510 [cal/mol]/RT) [s−1] and k2(T) = 2.66 × 1016 exp (−97880 [cal/mol]/RT) [s−1]. The resulting branching ratio, k1/(k1 + k2), ranges from 0.8 at 1350 K to 0.6 at 1800 K. 相似文献
567.
Shan Cheng Yu Qiao Jingchun Huang Wenxia Wang Zhenqi Wang Yun Yu Minghou Xu 《Proceedings of the Combustion Institute》2019,37(3):2715-2722
The study reports the effects of Ca and Na acetates on the transformation of nitrogen species during sewage sludge pyrolysis. Sludge samples, with or without acetates, were pyrolysed in a fix-bed reactor at 150–550 °C, and the nitrogen species in the pyrolysis products (char, tar, and gas) were characterised and quantified. Ca and Na acetates distinctly affect nitrogen transformation during sludge pyrolysis, which is ascribable to their different catalytic activities for the decomposition of nitrogen species in sludge. The addition of Ca acetate is found to increase nitrogen retention in char and reduce the formation of nitrogen species in tar, which is mainly due to the suppressed decomposition of protein-N as well as the promoted formation of stable nitrogen species in char. On the other hand, the addition of Na acetate enhances the decomposition of nitrogen species in sludge, such as protein- and inorganic-N. The levels of both Ca and Na acetates are significantly reduced in the nitrogen-containing gas emissions because acetone is produced when acetates are heated, and acetone readily reacts with NH3 to produce binary clusters or amines. Our results show that acetate addition is an important strategy for the reduction of NH3 emission during sludge pyrolysis. 相似文献
568.
569.
《Arabian Journal of Chemistry》2023,16(6):104717
Huge plastic consumption and depletion of fossil fuels are at the top of the world's environmental and energy challenges. The scientific community has tackled these issues through different approaches. Catalytic pyrolysis of plastic wastes to valuable products has been proved as a sustainable route which fits with the circular economy aspects. The design of catalytic materials is the central factor for performing the catalytic conversion of plastic wastes. This review aims to conduct a Bibliometric analysis of the pyrolysis of plastic wastes and non-precious-based catalysts by mapping research studies over the last fifty years. The analysis was developed via VOSviewer and RStudio tools. It showed the historical progress regarding plastic waste pyrolysis to produce valuable products and chemicals worldwide. The research shows that the top five countries with the highest citations and publications in this field were Spain, China, England, the USA and India. The Journal of Analytical and Applied Pyrolysis had the most comprehensive coverage of plastic waste. The relationship between the catalyst and the mechanism of plastic waste can influence the production yield and selectivity. The research gap and underrepresented research topics were identified, and previous research studies on developing non-precious-based catalysts that were most relevant to the current topic were reviewed and discussed. The challenges and perspectives on catalyst preparation and development for material complexity were critically discussed. Challenges of previous studies and directions for future research were provided. This report might guide the reader to take a general look at plastic waste valorization by pyrolysis and easily understand the main challenges. 相似文献