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This study analyzed the effect of the shale boom on the olefin industries. We investigated the paths by which US natural gas prices are transferred to ethylene and propylene prices and identified the price determinants based on the supply and demand conditions of each commodity's market. By comparing with the Japanese markets, the understanding of the supply structure of the ethylene and propylene industries is broadened. A path analysis framework was constructed to reflect the supply chains and applied to 2009–2018 data. Results showed that the downward trend in ethane prices provoked by the US shale boom reduced ethylene prices and raised propylene prices. Propane still serves as a determinant of the latter, while naphtha has lost predictive power for both. The comparative data confirmed that the US produces most of its petrochemicals from natural gas and gas-based feedstocks, while Japan relies on crude oil and refined naphtha. [ABSTRACT FROM AUTHOR]

Abstract We examined the carbon isotopic and molecular compositions of residual gases within Miocene methane-derived carbonates collected in Japan. Methane, ethane, and propane were extracted by acid digestion of powdered carbonates. The isotopic and molecular compositions of the extracted hydrocarbons are inconsistent with conventional thermogenic and microbial gases. Despite a range of δ13C values from −67‰ to −38‰ (relative to Vienna Pee Dee Belemnite (VPDB)), the liberated hydrocarbons yielded consistently low methane to ethane + propane ratios (2–30). The extracted ethane and propane yielded anomalous δ13C values as low as −84‰, lower than those of the coexisting methane. The ethane and propane were most likely produced through thermal cracking of organic compounds preserved within the seep carbonates during burial. The observed unusual isotopic trends may be explained by the mixing of two thermogenic gas components with different carbon isotopic and molecular compositions. Nevertheless, a positive correlation between δ13C values of methane and relatively immature carbonates at one study site (Nakanomata) indicates that while methane was oxidized to bicarbonate from which carbonates precipitated, it was preserved within the host carbonate cements. Such a scenario indicates that the residual methane at least partly originates from the Miocene seep fluid. Smaller amounts of methane were also released during heating and crushing of chipped samples. The results suggest that methane was entrapped mainly within intracrystal inclusions, which is supported by the observation of abundant nanometer-scale voids in an individual crystal. Highlights • Hydrocarbon gases were extracted from Miocene methane-seep carbonates in Japan. • Most hydrocarbons are thermogenic gases produced from organic matter in carbonates. • The original seep methane could partly be preserved in immature carbonate crystals. [ABSTRACT FROM AUTHOR]

Tetrachloroethylene (PCE) is one of the most common groundwater contaminants in Japan. PCE can be completely dechlorinated to ethylene (ETY) and ethane (ETA) by anaerobic microorganisms in the presence of asuitable electron donor. This study was conducted to examine the feasibility of using an anaerobic filter for the degradation of PCE in abioremediation process. Laboratory-scale anaerobic filters were operated at 25 deg. C using ethanol as the electron donor. Rapid start-upof the reactors was achieved by using anaerobic completely PCE-dechlorinating enrichment cultures as the inoculum. During the continuous operating periods, low concentrations (2.8 mg/L) of PCE were almost completely dechlorinated to ETY and ETA at hydraulic retention times of 49-15 hours with 100 mgCOD/L of ethanol. PCE concentrations as highas 80 mg/L was dechlorinated to ETY with a relatively low supply (200 mgCOD/L) of ethanol. Results of this study suggest that the anaerobic filter system is a feasible bioremediation process for the cleanupof groundwater which is contaminated by chlorinated ethylenes. [ABSTRACT FROM AUTHOR]