Experimental studies are carried out on a SEMICLATHRATE hydrate system of carbon dioxide in tetra-n-butylammonium bromide (TBAB) with a small amount of surfactant, sodium dodecyl sulfate (SDS), for 5, 10, and 20 wt.% TBAB to determine the phase equilibrium temperature and pressure conditions. It is observed that the presence of SDS did not influence the equilibrium conditions of the SEMICLATHRATE hydrate. Re-nucleation (memory) effect of SEMICLATHRATE HYDRATES of CO2 is studied for few cases of TBAB concentration in an aqueous solution. The equilibrium pressure and temperature conditions obtained for memory effect and regular experimental run without memory effect were observed to be quite close. It is concluded that in the case of no memory effect, with increasing TBAB percentage in the system, the time required for nucleation is reduced. For the same TBAB concentration, the incipient pressure and temperature required for nucleation and re-nucleation of SEMICLATHRATE HYDRATES increase while the time required for re-nucleation decreases.

Induction time and the amount of gas consumed, two important kinetic parameters in gas hydrate formation process, were investigated for the systems of water + methane and water + TBAC + methane, in this research. In order to study the effect of TBAC on the kinetics of methane hydrate formation, three aqueous solutions of TBAC with concentrations of (0, 3, and 5) wt% were prepared. The experiments were carried out (or done) in a 169 cm3 batch reactor and at a temperature of 278.15 K and initial pressures of (6.5 and 8) MPa. The results showed that adding TBAC decreases the induction time of hydrate formation process. The utilization of TBAC with concentration of 3 wt% at 8 MPa decreases the induction time from 437 min to 3 min and increases the amount of gas consumed during hydrate formation %47.09, compared to pure water. The experimental results showed that by increasing the pressure form 6.5 MPa to 8 MPa, the induction time of methane hydrate formation decreases, and the amount of methane consumed increases. In addition, by increasing the pressure form 6.5 MPa to 8 MPa in aqueous solution of TBAC with concentration of 3 wt%, the induction time decreases from 41 min to 4.12 min and the amount of methane consumed increases from 20.98 mmol/mol of solution to 28.29 mmol/mol of solution.

SEMICLATHRATE hydrate formers such as tetra-n-butylammonium bromide (TBAB), chloride (TBAC) and fluoride (TBAF) are promising compounds that mild the thermodynamic conditions of gas HYDRATES, considerably. The Clausius-Clapeyron equation is employed in this manuscript to calculate the dissociation enthalpies of methane/carbon dioxide/nitrogen + TBAF SEMICLATHRATE HYDRATES. A 460 cm3 stirred batch reactor was used to measure the phase equilibria of gas + TBAF SEMICLATHRATE HYDRATES at various concentrations of tetra-n-butylammonium fluoride. The dissociation P-T data were obtained using an isochoric pressure-search method in the temperature range of 275.15 to 304.7 K and the pressure range of 0.53 to 10.24 MPa at 0.0 - 0.4482 mass fraction of TBAF. Investigating the obtained dissociation data showed that the addition of TBAF to the solution increases the amount of dissociation enthalpy of SEMICLATHRATE HYDRATES per mole of the hydrated gas. Increasing the mass fraction of tetra-n-butylammonium fluoride, showed a straight relation with the amount of dissociation enthalpy per mole of hydrated gas.

According to Kyoto protocol، carbon dioxide is one of the six large greenhouse gases which causes global warming. Therefor it is very important to prevent it from entering the atmosphere. The gas hydrate technology is one of the newest methods of carbon dioxide separation، but slow kinetics of this technology is one of the major obstacles to industrialize the process. The induction time of carbon dioxide hydrate formation and the amount of gas have been consumed for the systems of water + carbon dioxide and water + TBAF + carbon dioxide were measured in this research. The experiments were done in a 169 cm3 batch reactor and at temperature 278. 15 K and initial pressure 3. 8 MPa. Utilization of 5 wt% TBAF decreases the induction time of hydrate formation from 73 min to 0. 9 min. The amount of carbon dioxide consumed within 40 min and 350 min of experiments was measured and reported. Utilization of 1، 4، and 5 wt% TBAF within 40 min of experiments increase the amount of carbon dioxide consumed 18. 5%، 39. 3%، and 71. 9%، respectively.

Gas HYDRATES could provide a clean and sustainable option to meet global energy demands. Accelerating gas hydrate formation is crucial to exploiting its positive applications, as these ice-like structures can serve as a vast and clean source of energy. In this research, we delve into the influence of sodium dodecyl sulfate (SDS) on the growth rate of double tetra n-butylammonium chloride (TBAC) + methane SEMICLATHRATE hydrate. To investigate this, we conducted experiments utilizing a stirred batch cell with a total volume of 169 cm3. The cell's temperature was maintained at 278.15 K, while the initial pressures were set at 6 and 8 MPa. Comparing the results with pure water, SDS showed a significant positive effect on the growth rate of methane hydrate formation. However, when 400 ppm of SDS was introduced, it had a detrimental impact on the average growth rate of the double (TBAC + methane) SEMICLATHRATE hydrate within just 50 minutes of the process.

Density functional theory (DFT) was used to study the chemoselectivity of acetylene hydratase in hydration of 3-butyn-2-ol, propargyl alcohol and propen. A quite large model of the enzyme’, s active site was made, based on its crystal structure. Geometrical structures of the stationary points along the reaction paths were optimized, and energy profiles of the reactions were obtained. The results showed that the binding energy of 3-butyn-2-ol is 16. 1 kcal/mol higher than the binding energy of the enzyme’, s normal substrate (acetylene), but the corresponding reactant is 17. 4 kcal/mol more stable. Similarly, propargyl alcohol’, s binding energy is 10. 7 kcal/mol more than binding energy of acetylene. In the third step of the reaction, propargyl alcohol reaches to a very stable intermediate and its reaction stops. These show that 3-butyn-2-ol and propargyl alcohol act as competitive inhibitors of acetylene hydratase. The results showed that binding of propen is very endothermic than binding of the other compounds (30. 3 kcal/mol). In addition, the next nucleophilic attack is also very endothermic. In summary, propen cannot be hydrated by acetylene hydratase.

Hydrogen storage in large quantities is a main factor to produce ‘‘Hydrogen Economy’’. Recently, with the development of the hydrogen economy and fuel cell vehicles, the manner of storing and delivering large quantities of hydrogen arises as a major problem. Nowadays several hydrogen storage methods are available. Technologies are being developed and/or engineered other than the classical compression and liquefaction of hydrogen, which are based on the chemical (e.g., ammonia) and physical (e.g., carbon nanotubes) adsorption of H2. Also, a novel technology is in progress, which is based on clathrate HYDRATES of hydrogen. In this article has been tried to discuss at length the possibility of hydrogen storage in hydrate and thermodynamic models.

Natural gases HYDRATES are crystalline solids composed of water and gas that are categorized in the clathrate family. Although gas HYDRATES have been discovered since 200 ago gas hydrate resources have only been discovered under see beds and frozen ocean zones only some 50 years ago. Since the 1979's extensive work has been focused on regasification of gas HYDRATES, due to the large resources of these materials as well as the limitations and costs of the others. Governmental initiatives have hence been developed in countries of high demand and limited resources. On the other hand, blocking of gas pipelines due to the formation of gas HYDRATES has embarked on an independent series of research experiments to inhibit the formation of the compounds, leading to the current status in which different companies perform research on diverse aspects of this field.The present work focuses on the technology trends and policy makings in this area through the search, retrieval and analysis of the patents and applications filed in the different fields (including hydrate formation, production, dissociation, degasification etc.). The results contain priceless information of the technology trends and research orientations in the field and can be of benefit to R& D planners, as well as researchers.The aim of this study is to investigate the hydrate technology trend by mining the patent information in the field of gas HYDRATES including "Inhibition of hydrate formation, hydrate production, hydrate dissociation and regasification, gas hydrate resources exploitation, and some HYDRATES applications" and analysis thereof in strategic and competitive levels. The analysis of the acquired information is of great value to determine the research and technology orientation in the field and to recognize the inventors active in the field.