Liu Quanyou,Peng Weilong,Meng Qingqiang,Zhu Dongya,Jin Zhijun,Wu Xiaoqi
Thermochemical sulfate reduction (TSR) is common in marine carbonate gas reservoirs, leading to complicated isotope characteristics of TSR-altered gas. This study aims to better understand how TSR affects the geochemical and isotopic compositions of alkanes in pyrolysis products. Pyrolysis of TSR were conducted with crude oil, nonane (C 9 ) and methylnaphthalene (MN) in the presence of MgSO 4 solution at temperatures of 350 °C, 360 °C, and 370 °C for different durations of 4–219 h in a closed system. Results show that carbon and hydrogen isotope compositions of alkane gas resulting from TSR (pyrolysis with crude oil and MgSO 4 ) became heavier with increasing carbon number, i.e., δ 13 C 1 < δ 13 C 2 < δ 13 C 3 and δ 2 H–C 1 < δ 2 H–C 2 < δ 2 H–C 3 . Compared with the δ 13 C 1 , δ 13 C 2 and δ 13 C 3 increased in a much wider range as heating continued. Carbon and hydrogen isotopes of alkane gas produced by TSR became heavier with increasing gas souring index. Values for δ 13 C 1 –δ 13 C 2 and δ 2 H–C 1 – δ 2 H–C 2 typically decreased as oil and C 9 underwent thermal cracking. Comparative experiments using C 9 in the presence of MgSO 4 produced partially reversed carbon isotope series (δ 13 C 1 > δ 13 C 2 ), which, for the first time, confirmed the ability of TSR to cause isotopic reversal from pyrolysis. The residual heavy alkanes gradually became 13 C-enriched during TSR, which increased δ 13 C 2 values and changed the partially reversed isotope sequence to a positive sequence (δ 13 C 1 < δ 13 C 2 ). The discovery of a partial reversal of the carbon isotope series of alkane gases through pyrolysis will further deepen the understanding of TSR-altered natural gas.
The preparation of biomass flame retardants with efficient flame-retardant properties is conducive to the realization of sustainable development and is of great practical significance. In this work, a green and sustainable biomass flame retardant PATAPEI was prepared by using phytic acid (PA), tannic acid (TA), and polyethyleneimine (PEI) as reactants via a one-step method to develop biomass flame retardants that can synchronize enhanced flame retardation, smoke suppression, and mechanical performance of epoxy resin (EP). The EP with only a 3% PATAPEI (EP/3PTP) has a LOI value of 28.5% with a UL-94 V-0 classification. The peak heat release rate (PHRR), total heat release (THR), and total smoke release (TSR) of EP/3PTP were decreased by 29.72%, 25.80%, and 21.16%, respectively, in comparison with the ones of pure EP. Additionally, the tensile and impact strengths of EP/3PTP are higher than the ones of pure EP. PATAPEI on heating decomposes to produce phosphorus-containing acids and biphenyltriol-containing compounds, which promote to form a good char layer with the aromatic structures during the combustion of EP/3PTP. Therefore, PATAPEI has prospects of wide application in the development of sustainable biomass flame retardant EP.
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