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We report H2 adsorption capacities reaching 0.05 wt % at 303 K and at 1 atm H2 pressure on solid-state CuCl-exchanged [Al]-SSZ-13 and [B]-SSZ-13 zeolites. Differential heat of H2 adsorption is found in the range between 16 and 48 kJ mol H2–1 on Cu(I)-SSZ-13 at 323 K and isosteric heat of adsorption is found between 20 and 55 kJ mol H2–1 on Cu(I)-[B]-SSZ-13 at temperatures between 293 and 323 K. Strong interactions between H2 and the copper cations in Cu(I)-SSZ-13 are evidenced using Rietveld refinements of neutron powder diffraction patterns revealing Cu–deuterium (D2) distances of 2.3(2) and 2.41(1) A. A temperature-dependent Cu(I) migration—away from the six-membered ring (6MR) and eight-membered ring (8MR)—is related to the high adsorption capacities of the samples at 303 K. At 10 K, access to Cu(I) at 6MR is sterically hindered by framework oxygen atoms (Cu–Oframework distance of 2.196(5) A), rationalizing the low H2 adsorption capacities of Cu(I)-SSZ-13 samples as compared to Na-SSZ-13 at 77 K.

Among all the basic SI units, the mass unit is the only one to be defined in terms of a material standard: a prototype called K. All the industrial countries possess their own standards which were compared to the K during the last international comparison showing that unknown evolution occurs, but the adsorption-desorption of cleaning products plays a relatively important role. A few years ago, several laboratories in the U.S.A., Germany, and France reported interesting results of photothermal measurements to detect desorption at normal temperature and pressure (NTP). This paper presents a mirage set-up built to detect the film of condensable gasses on metallic surfaces at NTP conditions. In order to quantify these measurements, an inverse method has been developed to determine the adsorption isotherm involved in the physical process of adsorption-desorption and the linked parameters such as absorbability, type of adsorption, and differential heat of adsorption. The results will be discussed to imagine possible tracks to reduce the instabilities of the standards in the future and for possible new definitions of standards built with silicon.

1. Study has been made of the isotherms for krypton adsorption on type X zeolites at −50, −93, and −120°C and the accompanying changes in the dimensions of the zeolite granule resulting from this adsorption. 2. For the adsorption of krypton on zeolite NaX at −93°C, the alteration of the zeolite granule dimensions and the differential heat of adsorption are similarly affected by changes in the degree of filling. 3. At low degree of filling, the contraction of NaX zeolites increases with rising temperature.

In this paper, the thermodynamic properties of lithium nitrate-ammonia mixtures are presented. The vapour pressure-temperature correlations are developed by fitting the experimental P-T-x data. The enthalpy of solution, the latent heat of vaporization, the integral heat of solution and the differential heat of solution are presented in appropriate tabular and graphical forms.

Heat transmission studies were performed using a test unit designed to evaluate temperature profiles generated during hydriding and dehydriding reactions in a single metal hydride bed. By solving differential heat balance equations it is possible to predict temperature profiles, hydrogen gas transfer and temperature changes in heat transfer fluids. The computed results are in good agreement with the experimental data. The maximum error in the computed bed temperature was 4 °C and the hydrogen flow rates were estimated with a maximum error of 15%.

The differential heat of absorption of hydrogen in zirconium has been measured by means of isoperibol calorimetry in the range of hydrogen concentration 0-0.5 H/Zr at temperatures 873-1123K. In the alpha phase the differential heat decreases with increasing hydrogen concentration except for an increase at very small concentrations but, in contrast, increases in the alpha + beta and beta phases, varying between 0.35 and 0.90 eV. Changes in the differential heat due to changes in elastic constants, lattice parameters and Fermi energy accompanying the absorption of hydrogen have been calculated and compared with the experimental result. The change in Fermi energy is a major contribution to the change in the differential heat.

The thermodynamic properties of selected hydrides of intermetallic compounds are measured using a gas-solid equilibration apparatus (Sievert's) coupled to a Tian-Calvet differential calorimeter. This combination allows simultaneous measurement of enthalpy changes and Gibb's energy; the differential configuration eliminates the pΔV correction. The experimental technique and apparatus are briefly described and the limits to accurate measurements are discussed. Preliminary small-sample measurements of the partial molar enthalpies of hydrogen in the two-phase coexistence region of the systems LaNi5 + H2 and CaNi5 + H2 have been performed.

The adsorption of nitrogen on evaporated iron films at 77 K or 90 K is studied by measuring the amount adsorbed, the equilibrium pressure, the change in resistivity of the iron films, the differential heat of adsorption and the thermal desorption. Four different adsorption states were found. By means of isotopic exchange measurements it could be seen that the nitrogen adsorption is nondissociative. There is strong evidence that the adsorption of nitrogen on iron is face specific.

The equilibrium sorption of a purified direct dye on natural cotton yarn has been determined over a range of dye-bath concentrations (20 to 175 mgm. of dye per litre of solution) and temperatures (75° to 90 °C.). The liquor-to-yarn ratio in the dye bath, which contained sodium chloride (4.00 gm. per litre), was sufficiently high to permit the concentration of dye in solution to remain essentially constant throughout a dyeing experiment. The dye was removed from the skeins using a pyridine–ethanol–water solution, and the concentration of dye in the latter determined spectrophotometrically.Differential heats of dyeing may be calculated from the results obtained. For an equilibrium sorption of 475 mgm. of Calcodur Blue 4GL per 100 gm. of natural cotton yarn, the value of 15 kgm-cal. per mole was found, and it is shown that the differential heat of dyeing increases as the value of the equilibrium sorption decreases. The results are interpreted in the light of the modern view of the structure of cellulose.

The differential heat of adsorption of hydrogen on evaporated Ni films is calorimetrically measured as a function of coverage θ at 77°K and 273°K under ultrahigh vacuum conditions. At 77°K the heat of adsorption steadily decreases with increasing coverage. At 273°K a maximum of the heat of adsorption is observed in the region 0.5 1.

The differential heat of adsorption of oxygen on activated cocoanut charcoal has been measured over the low concentration range to 14 micromoles per gram, by means of an improved ice calorimeter and a new charcoal bulb, in which oxygen is introduced into the middle of the charcoal mass. At zero concentration, a heat of adsorption of 129.0 kcal. per mole of oxygen was found, dropping to 72.0 kcal. at approximately 6.0 micromoles per gram. The initial heat of adsorption is much higher than the highest value that has been obtained previously. This indicates that the plain charcoal bulb previously used permitted loss of heat from the calorimeter; consequently, the values for the initial heats of adsorption were low. The theoretical significance of the high initial heat is discussed briefly.

Surface soils from six ADAS long‐term experiments, including two on Andover series, were examined for K‐Ca exchange by exchange isotherm and calorimetric methods. Preference for K decreased in the order Worcester > Clwyd > Newport. The latter two acid soils showed ‘no preference’ and Ca preference respectively. Preference for K decreased with decreasing surface area and increasing surface charge density. The enthalpic factor favoured K preference in every soil, but the entropic factor favoured Ca preference in all but one soil. The magnitude of the enthalpic factor was greater than that of the entropic factor, resulting in K preference, in the Andover, Hanslope and Worcester soils, while the reverse was the case in the Newport soil. In the Clwyd soil, enthalpic and entropic forces were counterbalanced. These relative contributions were related to the interactions between clay mineralogy, pH and manurial history. Differential heat measurements, ‐d (ΔHx)/dx revealed exchange site heterogeneity in five of the soils. Five regions of constant ‐d (ΔHx)/dx were found, ranging from 6 to 12 kJ eq−1, a maximum of three occurring in any one soil. These were assigned to montmorillonite (two regions), mica, hydrous mica and vermiculitic mica surfaces. The 2: 1 phyllosilicate contents of the clay fractions of the whole soils calculated thus differed from those determined by XRD analysis of the clay fractions. Residual K decreased the cation exchange capacity of some of the soils but did not alter their surface areas. Its effect on K preference, K binding strength and the arrangement of the components of the system (the entropic factor) was complex. RESP-09033

MARSHALL and Bramston-Cook (J.A.C.S., 51, 2019; 1929) have measured the differential heat of adsorption of oxygen on activated charcoal and conclude that the heat of adsorption approaches a maximum value of 89,600 cal. per gm. mol. of oxygen as the amount of gas adsorbed approaches negligible dimensions. They refer to the work of Garner and McKie (J. Chem. Soc., 130, 2451; 1927; cf. Far. Soc., 461; 1926), who found at low surface concentrations a heat of adsorption of 5000 cal./mol., and observed that the heat rose to a maximum value of 71,000 cal. as the surface concentration of oxygen increased and then fell off at still higher concentrations. These values were given by an experimental arrangement in which a thermocouple was embedded in the middle of a mass of charcoal. Marshall and Bramston-Cook suggest that it is desirable to repeat this work with thermocouples placed at different points throughout the charcoal.

The infra-red spectra of water adsorbed by X-type zeolites containing different alkali-metal cations have been studied. With small amounts of adsorption in LiNaX, NaX and KNaX zeolites water molecules interact mainly with the zeolite cations. The spectra show that one hydroxyl group of an adsorbed water molecule is bound to the oxygen of the zeolite skeleton and the other is “free”. In the case of CsX zeolite, where adsorption is weaker, both hydroxyl groups of the adsorbed water molecules interact, presumably, with the oxygen atoms of the zeolite. The relative amounts of water molecules interacting with the exchange cations, zeolite oxygen atoms and water molecules forming mutual hydrogen bonds depend on the cation and the number of water molecules in the zeolite cages. As these are filled there is a change in the energy of hydrogen bond formation between water molecules and the zeolite oxygen skeleton and between one another. This change becomes particularly apparent in the case of KX zeolite and is in accordance with the wave-like change of the differential heat of water adsorbtion by KX zeolite and with the maxima and minima of the heat capacity of adsorbed water.