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We present the critical analysis of the utilization of CO2 adsorption calorimetry/volumetry and TPD-CO2 for the determination of the Mg–Al mixed oxide basicity. The aim of work is the description and the evaluation of both methods with respect to the fact when the same types of CO2 adsorption complexes are involved. Critical parts of basic sites determination are originally discussed for both methods. In TPD-CO2, the process of the purging of non-specifically physisorbed CO2 is stressed. In CO2 adsorption calorimetry, the differential heat of CO2 distinguishing CO2 adsorption on weak basic sites and non-specific CO2 physisorption is stressed. Both methods are applied on series of selected Mg/Al mixed oxides varying in Mg/Al molar ratio and alkali co-cation. We show that the generally used TPD-CO2 does not provide complete information about basic sites since some weak sites form unstable CO2 species and these species could not be involved in TPD experiments. All our TPD-CO2 experiments reflect at 0–485 °C those CO2 adsorbed in the range of the differential heat of CO2 above 30–32 kJ mol−1.

The isotherms and differential heats of water vapor adsorption on Na- and Ca-saponite samples are measured. It is shown that the successive stages of hydration of the internal surface of this mineral appear as waves or inflections in the adsorption isotherms and maxima in the dependences of the differential heat on the adsorption value. The compositions of Na+ and Ca2+ aquacations in single- and double-layer saponite hydrates are determined. The heats of interaction between water molecules and interlayer Na+ cations in single-layer saponite hydrates and between Na+ cations and the ion exchanger matrix are estimated.

The interactions of carbon monoxide with Lewis acid sites of zeolites were investigated using microcalorimetric and temperature programmed desorption (TPD) techniques. Carbon monoxide was adsorbed at 25°C on transition-metal ion-exchanged FAU (Y and X) and MOR type zeolites. The differential heats of adsorption ( Q dif ) indicate the heterogeneity of the acid sites, in all the investigated systems. The specific interactions of CO with the strongest acid sites were recognized. The results of TPD confirm that CO molecules were adsorbed on the sites of different strength.

The curve for the differential heat of adsorption of water on γ aluminum oxide has parts related to the interaction of the adsorbed water molecules with surface molecules of coordinated water and with acid and basic hydroxyl groups. Estimates have been made of the effective charges and hydration numbers for three of these adsorption centers. Textural changes have been observed in the γ-Al2O3 particles related to interplate swelling in the secondary sorbent packets into which the primary particles are linked.

Solutions of blockcopolymers (POE-b-PI-b-POE) in fluids of interacting aqueous nanodroplets (W/O microemulsions) are studied. The interaction strength between the (pseudo) two components is measured by the shift of the percolation temperature relative to that of the pure microemulsion. A quantitative measure of the interaction, the differential heat of solution, is thermodynamically related to the slopes of the equilibrium temperature of the system with varying monomeric nanodroplet concentration and the experimental percolation line in the presence of copolymer.

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.

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.

The differential heats of adsorption of ammonia on solid acids were measured, and the surface acid strength distribution and acidity were evaluated. The solid acids studied were silicaalumina, zeolite-containing silica-alumina, sodium-poisoned silica-alumina, alumina and silica. Steam-treatment of these solid acids resulted in a reduction of about 50% in acid density and the disappearance of strong adsorption sites of higher than 120kJ/mol for the heat of adsorption of ammonia. However, it did not affect the positions of the maximum and minimum of the site energy distribution curve. The cumene cracking activity increased linearly with the number of acid sites higher than 70kJ/mol for the heat of adsorption of ammonia. Zeolite-containing silica-alumina showed much higher activity than that of silica-alumina.

The sensitivity and reliability of the improved-flow micro-calorimeter have been examined by supplying given amounts of electric energy to the calibration heater inserted in the calorimeter. The detection limit of the heat amount was found to be 0.01 meal, and its probable error to be ±0.5 and ±0.3% at the heat evolutions of 10 and 40 meal respectively. The heat of the adsorption of benzene on silica gel from a cyclohexane solution has been measured at 30°C by the calorimeter thus constructed. The adsorption calorimetry indicates that benzene is adsorbed reversibly on silica gel, and that the differential heat of the adsorption of benzene is independent of the amount of adsorbed benzene, but that it depends strongly on the pretreatment temperature of the silica gel. The heats of adsorption were found to be 1.2, 1.6, 2.0, and 3.8 kcal/mol on silica gel samples treated at 100, 300, 500, and 800°C respectively. The findings on the heats of adsorption have been elucidated in terms of the interaction between b...

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.

A quantitative study has been made of the exchange of Li+, K+, Rb+, Cs+, Ag+, Tl+, NH4+, Ca2+, Sr2+, Ba2+ and Pb2+ with Na+ in a natural chabazite. All the ions except Cs+ exchanged almost completely with Na+. From the isotherm contours, Kielland plots and differential heat curves attempts have been made to determine cation positions in the zeolite. For the ions that exchange almost completely the thermodynamic affinity sequence, based on the standard free energies of exchange, is Tl+ > K+ > Ag+ > Rb+ > NH4+ > Pb2+ > Na+ = Ba2+ > Sr2+ > Ca2+ > Li+. Heats of exchange were determined calorimetrically and were negative when K+, Rb+, Cs+, Ag+, Tl+ and NH4+ in the zeolite, and positive when Na+ was replaced by Li+, Ba2+ and Pb2+. Exchanges involving Ca2+ and Sr2+ were so slow that it was not possible to determine equilibrium heats of exchange.

The present paper consists of an attempt to interpret theoretically the experiments of Solbakken and Reyerson on the magnetic susceptibility of nitric oxide adsorbed on silica gel. A primitive model is used in which the axis of the NO molecule is regarded as frozen in space and the crystalline field mixes the 3II1/2 and 3II3/2 states. To explain the experimental data it is necessary that the size of the crystalline potential increase with temperature. Possible justification of this assumption is found in the fact that the observed differential heat of adsorption increases with temperature. More refined calculations do not seem warranted in the absence of magnetic data over a wider temperature range including possibly magnetic resonance measurements.

Solid super acids were prepared by the reaction of gaseous antimony pentafluoride with silica–alumina and heats of adsorption of ammonia on their surfaces were measured. Solid super acids gave about 170 kJ/mol of an initial differential heat of adsorption and their adsorption energies were mainly distributed in the vicinity of 137 kJ/mol, while the initial differential heat of adsorption on original silica–alumina was about 150 kJ/mol and its adsorption energy was chiefly distributed in the vicinity of 117 kJ/mol. Therefore, it was shown that solid super acid had stronger, more homogeneous and much more acid sites than original silica–alumina.

The differential heat of adsorption of cyclopentane is a complex function of the occupancy. This effect presumably is a consequence of the geometrical relationship between the adsorbed molecules and the silicalite pores.

Solid super acids were prepared by the reaction of gaseous antimony pentafluoride with silica–alumina and heats of adsorption of ammonia on their surfaces were measured. Solid super acids gave about 170 kJ/mol of an initial differential heat of adsorption and their adsorption energies were mainly distributed in the vicinity of 137 kJ/mol, while the initial differential heat of adsorption on original silica–alumina was about 150 kJ/mol and its adsorption energy was chiefly distributed in the vicinity of 117 kJ/mol. Therefore, it was shown that solid super acid had stronger, more homogeneous and much more acid sites than original silica–alumina.

Differential heats of adsorption, text-decoration:overlineqv, of different amounts of water vapour, ns, have been measured in a double calorimeter at 23, 40, 60 and 100°C on KNaX zeolite and at 100°C on NaX zeolite. The mechanism of successive filling of different energy sites in the cavities of KNaX zeolite by water molecules at 23°C was shown earlier by the wave-shaped change in text-decoration:overlineqv, by the change in heat capacity and by the shift of band frequency in the i.r. spectrum of adsorbed water. The wave-shaped change in text-decoration:overlineqv is replaced by a monotonic one as the temperature rises. At 100°C, text-decoration:overlineqv smoothly decreases with increase in ns; the qv values for both zeolites are close. The differential heat capacities of adsorbed water, text-decoration:overlineC, determined from the text-decoration:overlineqv measurements at different temperatures and ns values, are close to those measured directly. The dependence of text-decoration:overlineC on temperature has been estimated. The isotherms of water adsorption on these zeolites have also been considered.

The presence of superacidic sites in fluorinated H-mordenite has been proved by calorimetric measurement of the differential heat of ammonia adsorption, catalytic testing for paraffin conversion at low temperatures and by means of the indicator test.

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.