In this study, the equilibrium data of the hydrates forming in tetra-n-butylphosphonium bromide (TBPB) aqueous solution with and without carbon dioxide (CO2) are measured at mass fractions w = (0.10, 0.20, 0.35, and 0.50) in the pressure range of (0.4 to 4.0) MPa and in the temperature range of (281.0 to 292.0) K. Meanwhile, the crystal morphologies of TBPB hydrates with and without CO2 are visually observed. The equilibrium data and morphologies of TBPB hydrates are compared with those of tetra-n-butylammonium bromide (TBAB) hydrates.

In the present study, the phase equilibrium conditions of tetra-n-butylphosphonium bromide (TBPB) hydrate forming with carbon dioxide (CO 2 ) (0.17 mole fraction)/N 2 and CO 2 (0.6171 mole fraction)/N 2 gas mixtures and TBPB aqueous solution at mass fractions w = 0.05, 0.10, and 0.15 are measured in the pressure range from (0.6 to 4.3) MPa, respectively. The CO 2 separation efficiencies in a two-stage separation with TBPB hydrate are measured at 277.5 K in the initial pressure range of (2.0 to 4.0) MPa. Furthermore, three quaternary salts, i.e., tetra-n-butylammonium bromide (TBAB), tetra-n-butylammonium chloride (TBAC), and tetra-nbutylphosphonium chloride (TBPC), are adopted in the first-stage separation for comparison.

In the present study, CO 2 gas and tetra-n-butyl ammonium bromide (TBAB) is adopted to form CO 2 +TBAB double hydrate at mass fractions w = 0.05 and 0.10. The moles of CO 2 +TBAB double hydrate are calculated by the variation of pressure of CO 2 gas from initial pressure at about 4.03 MPa and the solubility of CO 2 in TBAB aqueous solution at various subcoolings of 2.0−5.0 K. In addition, the formation characteristics of CO 2 +TBAB double hydrate are observed by the visualization, and it is verified to be a type B double hydrate. The kinetics of CO 2 +TBAB double hydrate formation at w = 0.05 and 0.10 is determined by the normalized rate of hydrate formation in the hydration process.

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Using the staggered intercity but within-province deregulation of local banks in China as exogenous variations, we evaluate the effect of banking integration across geographical segmentation on capital misallocation. Based on an administrative data set comprehensively covering Chinese manufacturing firms, we find that for firms with initially high marginal revenue products of capital (MRPK), the integration increases physical capital by 19.3%, and reduces MRPK by 33.1% relative to low MRPK firms. Our findings are more pronounced for non-stated-owned firms and firms with higher exposure to integrated banks. Integration also significantly increases the responsiveness of firms’ investments to deposit shock on other cities within the same province.