There is still considerable controversy surrounding the mechanisms, thermodynamics, and kinetics of heavy oil aquathermolysis and pyrolysis processes. The present paper aims to widen our knowledge about the effect of iron tallates on pyrolysis and aquathermolysis of Cuban heavy oil. The obtained SARA (S: saturates, A: aromatics, R: resins, A: asphaltenes) analysis has shown a significant increase in light hydrocarbon content during aquathermolysis. Moreover, the elemental analysis has indicated an increase in C and H content by almost 4% and 6%, respectively, with a significant decrease in S and O content by up to 23% in the presence of iron tallates. These results have been further confirmed by infrared spectrometry. The obtained IR data indicated that asphaltene and resin compounds transform into light hydrocarbons after aquathermolysis. On another hand, the activation energy of heavy oil pyrolysis decreased in the presence of the utilized catalyst; meanwhile, the reaction rate increased, especially in the temperature range of 200–480 °C, which may validate a significant effect of the used catalyst in real conditions. Moreover, the obtained thermodynamic data showed a decrease in the enthalpy and entropy of activation of oil pyrolysis in the presence of iron tallates. Our results are encouraging in terms of energy consumption, optimization, and process control and should be validated by a larger sample size.

The first evidence of native cyclodextrins fusion was registered using fast scanning calorimetry (FSC) with heating rates up to 40,000 K s⁻¹. The endothermal effects, detected at low heating rates, correspond to the decomposition processes. Upon the increase of the heating rate the onset of these effects shifts to higher temperatures, reaching a limiting value at high heating rates. The limiting temperatures were identified as the melting points of α-, β- and γ-cyclodextrins, as the decomposition processes are suppressed at high heating rates. For γ-cyclodextrin the fusion enthalpy was measured. The activation energies of thermal decomposition of cyclodextrins were determined by dependence of the observed thermal effects on heating rates from 4 K min⁻¹ in conventional differential scanning calorimetry to 40,000 K s⁻¹ in FSC. The lower thermal stability and activation energy of decomposition of β-cyclodextrin than for the other two cyclodextrins were found, which may be explained by preliminary phase transition and chemical reaction without mass loss. The obtained values of fusion parameters of cyclodextrins are needed in theoretical models widely used for prediction of solubility and solution rates and in preparation of cyclodextrin inclusion compounds involving heating.

An efficient strategy of polymorph screening is offered for tert-butylthiacalix[4]arene tetrasubstituted with phenacyloxy groups (1), which is based on saturation of its guest-free solid samples and inclusion compounds with guest vapors inducing solid-solid phase transition, complete or partial exchange or repulsion of included guest. The offered approach makes the preparation of polymorphs more reproducible and predictable as the performed phase transitions are under mostly thermodynamic control even when giving metastable forms. Smart transformation of calixarene states was demonstrated where stable and metastable polymorphs are formed in a kind of on/off switching. Guest repulsion or solid-phase exchange with another guest vapor gives a guest-free form directly or a less stable inclusion compound is prepared that can release guests by drying under milder conditions without host collapse to a stable packing. In total, seven polymorphs of 1 were identified and characterized. Single crystal data reveal the polymorphophore features of 1, which help to variate its polymorphic state. The observed control of polymorphic transitions contributes to the comprehension of their causes and mechanism. The elaborated procedures enable an effective screening of polymorphs through a standardized treatment of the target compound on a click basis with a flexible variation of conditions, which may be scaled up to find more crystal forms.