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Solid-state refrigeration technology based on caloric effects are promising to replace the currently used vapor compression cycles. However, their application is restricted due to limited performances of caloric materials. Here, we have identified colossal barocaloric effects (CBCEs) in a class of disordered solids called plastic crystals. The obtained entropy changes are about 380 J kg -1 K -1 in the representative neopentylglycol around room temperature. Inelastic neutron scattering reveals that the CBCEs in plastic crystals are attributed to the combination of the vast molecular orientational disorder, giant compressibility and high anharmonic lattice dynamics. Our study establishes the microscopic scenario for CBCEs in plastic crystals and paves a new route to the next-generation solid-state refrigeration technology.

Phase equilibria (pressure−temperature relations) of the H2 + tetrahydrofuran mixed gas hydrate system have been measured for various concentrations of tetrahydrofuran aqueous solutions. The three-phase equilibrium lines obtained in the present study are shifted to the low-temperature or high-pressure side from that of the stoichiometric THF solution. Each three-phase equilibrium line of H2 + tetrahydrofuran hydrate converges at the three-phase equilibrium line of the pure tetrahydrofuran hydrate. At the cross point on the lines, the tetrahydrofuran concentration of mother aqueous solution agrees with each other. The Raman spectra of H2 and tetrahydrofuran for the H2 + tetrahydrofuran mixed gas hydrate do not change with the variation of tetrahydrofuran mole fraction from 0.010 to 0.130 in the aqueous solution.

Hydrogen hydrates with tetrahydrofuran (THF) as a promoter molecule are investigated to probe critical unresolved observations regarding cage occupancy and storage capacity. We adopted a new preparation method, mixing solid powdered THF with ice and pressurizing with hydrogen at 70 MPa and 255 +/- 2 K (these formation conditions are insufficient to form pure hydrogen hydrates). All results from Raman microprobe spectroscopy, powder X-ray diffraction, and gas volumetric analysis show a strong dependence of hydrogen storage capacity on THF composition. Contrary to numerous recent reports that claim it is impossible to store H(2) in large cages with promoters, this work shows that, below a THF mole fraction of 0.01, H(2) molecules can occupy the large cages of the THF+H(2) structure II hydrate. As a result, by manipulating the promoter THF content, the hydrogen storage capacity was increased to approximately 3.4 wt % in the THF+H(2) hydrate system. This study shows the tuning effect may be used and developed for future science and practical applications.

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The most important process to make hydrogen is based on steam reforming of natural gas according to an overall reaction CH 4 + 2H 2 O!4H 2 + CO 2 , where after reformation of the natural gas to a CO/H 2 mixture (syngas) a water-gas shift reaction results in a predominantly CO 2 /H 2 mixture. [1,2] Steam reforming potentially offers one technological path to extend the trend of decarbonization of the primary fossil fuel by taking advantage of the low 1:4 carbon-to-hydrogen ratio of methane compared to coal (~8:4) and oil (~2:4), provided that subsequent separation of the CO 2 /H 2 mixture and sequestration of CO 2 is cost-effective and feasible. We present here a guest-free hydroquinone (HQ) clathrate, prepared by gas-phase synthesis, which reveals unique selectivities towards CO 2 /CH 4 and CO 2 /H 2 mixtures. A dynamical pore-widening process allows CO 2 to be adsorbed with a selectivity of 29:1 from a CO 2 /CH 4 (50:50 v/v) mixture and with a selectivity of 60:1 reversibly stored at 7 MPa and 298 K in the presence of a CO 2 /H 2 (50:50 v/v) mixture. This first example of a flexible hydrogen-bonded organic framework (HOF) that can reversibly and selectively absorb and store CO 2 opens up a host of applications.The

Phase equilibria for the tetrahydrofuran + water system below atmospheric pressure were investigated in a temperature range from 272 K to 278 K. The three-phase (structure-II hydrate + aqueous solution + gas) equilibrium curve has a maximum temperature at 277.45 ± 0.02 K and a pressure of 4.9 ± 0.1 kPa. At this condition, the equilibrium tetrahydrofuran composition of aqueous solution is equal to the stoichiometric ratio of tetrahydrofuran hydrate (structure-II). The tetrahydrofuran hydrate does not coexist with the gas phase beyond 277.45 K. The four-phase (structure-II hydrate + aqueous solution + ice Ih + gas) equilibrium point exists at 272.06 ± 0.02 K and 1.1 ± 0.1 kPa, and the equilibrium tetrahydrofuran mole fraction of aqueous solution is 0.0106 ± 0.0002.

The thermodynamic stabilities of semiclathrate hydrates were investigated in the tetra-n-butyl ammonium chloride (TBAC) aqueous solution (mole fraction of TBAC is 0.0323) + H2, + N2, + CH4, + CO2, and + C2H6 systems. The dissociation temperature of each semiclathrate hydrate is higher than that of the simple TBAC semiclathrate hydrate (hydration number is 30) except for the C2H6-containing system in the whole pressure region under the present experimental conditions. Isobaric dissociation temperatures of the TBAC + H2, + N2, + CH4, and + CO2 hydrates increase in this order. The temperature−pressure projection indicated that the hydrate structural transition occurs around 3 MPa in the TBAC + CH4 semiclathrate hydrate system, while the three-phase equilibrium curves of the other TBAC hydrate systems do not show any discontinuity in gradient under the present conditions.