Mass Fraction Of Methanol Research Articles

Kinetic Characterization of Pt/Al2O3 Catalyst for Hydrogen Production via Methanol Aqueous-Phase Reforming

Compared to steam reforming, methanol aqueous-phase reforming (APR) converts methanol to hydrogen and carbon dioxide at lower temperatures, but also displays lower conversion rates. Herein, methanol APR is studied over the active Pt/Al2O3 catalyst under different operating conditions. Studies were conducted at different temperatures, pressures, methanol mass fractions, and residence times. APR performance was evaluated in terms of methanol conversion, hydrogen production rate, hydrogen selectivity, and by-product formation. The results revealed that an increase in operating pressure and methanol mass fraction had an adverse effect on the APR performance. Conversely, it was found that hydrogen selectivity was unaffected by the operating pressure and residence time for the methanol feed mass fraction of 5%. For the methanol feed mass fraction of 55%, hydrogen selectivity was improved by operating pressure and residence time. The alumina support phase change to boehmite as well as sintering and leaching of the catalytic particles were observed during catalyst stability experiments. Additionally, a comparison between methanol steam reforming (MSR) and APR was also performed.

Structural optimization calculation of methanol spiral tube reformer based on waste heat utilization and experimental verification of reactor performance

Spiral tube is compact, efficient in heat transfer and can make full use of the annular space in the engine, so it can be applied to heat recovery under a variety of operating conditions. This paper developed a three-rate, one-dimensional model combined with simulations, experiments. It can be found that in the hydrogen prediction, the model has an error of 10 % from experiment and 0.91 % from literature; the increase in length from 0.5 m to 1.35 m increases methanol conversion by 7.97 %; the increase in spiral diameter from 4 mm to 7 mm increases methanol conversion by 9.35%; spiral radius from 40 mm to 70 mm, methanol conversion rate decreased by 5%; mass fraction of methanol decreased by 16 % when the pitch was increased from 5 mm to 20 mm. When diameter is 4 mm, length is 1 m, the MSR reaction rate reach 24.1 mol/m3/s, methanol conversion rate is 87.91 %. When spiral pitch is 10 mm, spiral diameter is 40 mm, methanol conversion rate can reach 91.83 %. The spiral tube reactor has a compact structure and can achieve 87.19 % methanol conversion and 0.0955 L/min H2 production at WHSV = 0.9 h−1 and S/C = 1.7.

ZIF-67 Incorporated Sulfonated Poly (Aryl Ether Sulfone) Mixed Matrix Membranes for Pervaporation Separation of Methanol/Methyl Tert-Butyl Ether Mixture.

Mixed matrix membranes (MMMs) with nano-fillers dispersed in polymer matrix have been proposed as alternative pervaporation membrane materials. They possess both promising selectivity benefiting from the fillers and economical processing capabilities of polymers. ZIF-67 was synthesized and incorporated into the sulfonated poly (aryl ether sulfone) (SPES) matrix to prepare SPES/ZIF-67 mixed matrix membranes with different ZIF-67 mass fractions. The as-prepared membranes were used for pervaporation separation of methanol/methyl tert-butyl ether mixtures. X-ray diffraction (XRD), Scanning Electron Microscopy (SEM) and laser particle size analysis results show that ZIF-67 is successfully synthesized, and the particle size is mainly between 280 nm and 400 nm. The membranes were characterized by SEM, atomic force microscope (AFM), water contact angle, thermogravimetric analysis (TGA), mechanical property testing and positron annihilation technique (PAT), sorption and swelling experiments, and the pervaporation performance was also investigated. The results reveal that ZIF-67 particles disperse uniformly in the SPES matrix. The roughness and hydrophilicity are enhanced by ZIF-67 exposed on the membrane surface. The mixed matrix membrane has good thermal stability and mechanical properties, which can meet the requirements of pervaporation operation. The introduction of ZIF-67 effectively regulates the free volume parameters of the mixed matrix membrane. With increasing ZIF-67 mass fraction, the cavity radius and free volume fraction increase gradually. When the operating temperature is 40 °C, the flow rate is 50 L·h-1 and the mass fraction of methanol in feed is 15%, the mixed matrix membrane with ZIF-67 mass fraction of 20% shows the best comprehensive pervaporation performance. The total flux and separation factor reach 0.297 kg·m-2·h-1 and 2123, respectively.

Equilibrium solubility and modeling of Glibenclamide in cosolvent mixtures of Methanol, n-Propanol, Isopropanol, and Acetonitrile + Water

Equilibrium solubility of glibenclamide (GCM) in aqueous solutions of methanol, n-propanol, isopropanol, and acetonitrile were studied by static technique at temperatures ranging from 288.15 K to 323.15 K under p = 101.3 kPa. When the composition of cosolvent was constant in the four mixed solvents, GCM solubility increased with the rising temperature. When the temperature was fixed, the GCM mole fraction solubility showed positive dependence on the increasing mass fraction of methanol in methanol + water mixture. While in solutions of n-propanol + water, isopropanol + water, and acetonitrile + water, it first increased as the mass fraction of cosolvent (w) added, at around w = 0.9, the solubility reached a maximum value and then it descended. Thermodynamic models like Jouyban−Acree model, modified Apelblat−Jouyban−Acree model, and CNIBS/R-K model were taken to correlate the equilibrium mole fraction solubility of GCM in four solvent mixtures. The maximum RAD and the RMSD values calculated by the CNIBS/R-K model were found in the mixture of methanol + water and didn’t exceeded 7.4 × 10−2 and 1.48 × 10−5, respectively. However, the maximum RAD values obtained by the Jouyban−Acree and modified Apelblat−Jouyban−Acree model were found in the mixture of acetonitrile + water and didn’t exceeded 5.57 × 10−2 and 5.55 × 10−2, respectively. The RMSD all didn’t exceeded 2.54 × 10−5. Hence, the Jouyban−Acree model and modified Apelblat−Jouyban−Acree model are shown to be superior to the CNIBS/R-K model in this work. The experimental data and model parameters obtained will be helpful for the preparation and purification of GCM.

Innovative conceptional approach to quantify the potential benefits of gasoline-methanol blends and their conceptualization on fuzzy modeling

Restricted fossil-based petroleum fuel resources and a raising fuel utilization direction have produced significant economic and ecological issues. The current article exhibits a robust model of using the innovative conceptional approach to quantify the potential benefits from gasoline-methanol blends utilizing a Fuzzy model based on real experimental data. Methanol has several merits to be an appealing gasoline fuel surrogate. The compositions of gasoline utilized in the current study were gasoline Fisher-Tropsh samples (GFT), including GFT-100, GFT-95, GFT-90, GFT-85, GFT-80, GFT-75, GFT-70, GFT-65, and GFT-60 with a methanol mass fraction of 0%, 5%, 10%, 15%, 20%, 25%, 30%, 35%, and 40% by weight. Additionally, antiknock combustion characteristics of gasoline-methanol blends, involving research octane number (RON) and motor octane number (MON) at different percentages were investigated. The results showed that the established Fuzzy logic model is well matching the real experimental results to a great grade, presenting the trustworthiness of the Fuzzy logic model. Finally, the results reported that a low percentage of methanol blends is preferable to maximize the efficiency and exhaust emissions of motor gasoline engines without altering the material structure.

Nucleation Behavior in a Transformation of the Amorphous State to the Crystalline State during Antisolvent Crystallization

The liquid-mediated phase transformation of an amorphous form to a crystalline heptahydrate form of guanosine 5′-monophosphate was studied in antisolvent crystallization using methanol–water mixtures as solvents. Three steps were monitored: the formation of the amorphous form, dissolution of the amorphous form, and growth of the heptahydrate crystals using in situ Raman spectroscopy, focused beam reflectance measurement (FBRM), and particle vision measurement (PVM) and off-line methods like viscosity, thermal gravimetric analysis (TGA), and powder X-ray diffraction (PXRD). Effects of the antisolvent fraction, initial concentration, and addition rate of the antisolvent on the transformation process were discussed. Solid forms, solute concentration, particle size, counts, induction time, metastable zone width, solution viscosity, and amorphous slurry viscosity were all measured for 18 experiment runs. The induction time of the crystalline hydrate increased with the supersaturation but decreased with the increasing viscosity of the amorphous slurry. Both are not as expected. The induction time correlates nicely in the opposite direction with the viscosity of the amorphous slurry concentration. The amorphous slurry viscosity is about 20 times higher than the solution viscosity. Viscosity of the amorphous slurry was discovered to be a crucial factor influencing the transition of the amorphous slurry to the crystalline form in the pre-exponential component of the classical nucleation rate equation. The metastable zone boundaries of the amorphous and heptahydrate crystalline forms were shown in a plot of the solute concentration versus the mass fraction of methanol in the mixed solvent. The amorphous and heptahydrate crystalline forms can be selectively produced under all the conditions of this study. The pre-exponential factor of the nucleation rate equation factor is crucial in comprehending the transformation from an amorphous to a crystalline state.

Thermal Hydraulics and Thermochemical Design of Fatty Acid Methyl Ester (Biodiesel) Esterification Reactor by Heating with High Boiling Point Phenyl-Naphthalene Liquid

FAME (biodiesel) is an alternative fuel that can be produced from vegetable oils. There is growing interest in the research and development of renewable energy sources. A possible solution is a biofuel usable in compression-ignition engines (diesel engines) produced from biomass rich in fats and oils. This paper contains a new and safer design of an esterification reactor for producing FAME (biodiesel) by utilizing high boiling point fluid (called phenyl-naphthalene). CFD simulation of biodiesel production by using methyl imidazolium hydrogen sulfate ionic liquid has been carried out. Ionic liquids (ILs) are composed of anions and cations that exist as liquids at relatively low temperatures. They have many advantages, such as chemical and thermal stability, low flammability, and low vapor pressures. In this work, the ionic liquids have been applied in organic reactions as solvents and catalysts of the esterification reaction. The great qualities of high boiling temperature fluids, along with advances in the oil and gas industries, make the organic concept more suitable and safer (water coming into contact with liquid metal may cause a steam explosion hazard) for heating the esterification reactor. The COMSOL Multiphysics code has been employed and simultaneously solves the continuity, fluid flow, heat transfer, and diffusion with chemical reaction kinetics equations. It was shown that the heat flux could provide the necessary heat flux required for maintaining the esterification process. It was found that the mass fractions of methanol and oleic acid decrease along the reactor axis. The FAME mass fraction increased along the reactor axis. The maximal biodiesel yield obtained in the esterification reactor was 86%. This value is very similar to the experimental results obtained by Elsheikh et al.

Mathematical modeling of technological process in formalin production

Methods and algorithms of the sustainable synthesis of adaptive control systems for the technological process of formalin production have been proposed in this article. Parameters of the regulator are estimated in the developed adaptive control system, i.e. the purpose of adaptation is reduced to the estimation of coefficients of the regulator providing the specified behavior of the system. The results obtained and the analysis of transition processes based on the modeling of the control system showed that with adaptive control, mass fractions of formaldehyde and methanol in formalin are held within 36.5÷37.5% and 0.7÷0.9% respectively, while the specific consumption of the methanol decreases by 3÷4%, which allows the process in mode close to the optimal.

Chitosan‐Modified Polyvinyl Alcohol Membrane High Performance in Biodiesel/Methanol Pervaporation Separation

AbstractThe chitosan doped polyvinyl alcohol film are prepared by blending heating method. The prepared membrane is characterized by Fourier Transform Infrared Spectrometer (FTIR), scanning electron microscope (SEM), atomic force microscope (AFM) and universal testing machine. The surface of the cast membranes is generally flat, and the pervaporation process would cause the membrane to have a wrinkled shape. These membranes can be used for pervaporation to separate methanol/biodiesel mixtures. This paper studies the effects of different chitosan additions, feed temperature and feed concentration on membrane performance. When the chitosan doping amount is 30 % by mass of polyvinyl alcohol at 40 °C, the maximum flux reaches 569.212 g m−2 h−1. At the same time, the separation factor increases as the methanol concentration in the liquid decreases. When the methanol mass fraction is 10 %, the separation factor can reach 116.717.

The solubility profile and dissolution thermodynamic properties of minocycline hydrochloride in some pure and mixed solvents at several temperatures

The dissolution process of α-minocycline hydrochloride in different solvent within the temperature range from 273.15 K to 313.15 K was studied by using “isothermal saturation method” under atmospheric pressure. It is found that the minocycline hydrochloride is insoluble in ethyl acetate and acetonitrile compared with alcohols. The maximum “mole fraction solubility” of minocycline hydrochloride in methanol is 2.88 × 10−3 at 313.15 K and followed by ethanol is 1.90 × 10−3 at 313.15 K, n-propanol is 1.23 × 10−3 at 313.15 K, isopropanol is 2.10 × 10−4 at 313.15 K, acetonitrile is 7.78 × 10−5 at 313.15 K and ethyl acetate is 2.63 × 10−5 at 313.15 K. The higher solubility of minocycline hydrochloride in alcohols could be due to their ability to form hydrogen bonds with solute molecule compared with ethyl acetate and acetonitrile. However, in mixtures of ethyl acetate (1-w) + methanol (w), the solubility values increased firstly, and then decreased with the mass fraction (w) of methanol, the maximum data is 6.07 × 10−3 at w = 0.60 at 313.15 K, an increase about 230 fold. In dissolution process of a solute in pure or mixed, solute - solvent interactions are more significant among other interactions and should be considered in any interpretation of the solubility behaviour. In order to obtain a rough evaluation of the solute - solvent intermolecular interactions, the solvatochromic parameters of pure and mixed solvents were discussed. Moreover, the experimental solubility are correlated by the modified Apelblat equation and Jouyban-Acree’s model, and the values of relative average deviation (RAD) are all less than 0.76% in pure organic solvents, and no more than 6.80% in mixtures. Besides, the results of apparent thermodynamic analysis indicates that the dissolution is an endothermic and entropy driven process. The solubility data and thermodynamic properties would be useful in the process of purification, recrystallization and dosage form design in pharmaceutical industries.

Solubility of melatonin in ethyl acetate + (N, N-dimethylformamide, 2-methoxyethanol, 2-ethoxyethanol and methanol): Determination, correlation, thermodynamic properties and Hansen solubility parameter at saturation

For further study on solubility behaviors of melatonin (MT), the solubility of MT in the three mono-solvents {N, N-dimethylformamide (DMF), 2-methoxyethanol, 2-ethoxyethanol} and four binary solvents {(DMF, 2-methoxyethanol, 2-ethoxyethanol and methanol) + ethyl acetate} was measured in a range of 278.15 K–323.15 K by laser monitoring method. The measurement results showed that MT solubility in all tested solvents increased with rising temperature. In binary solvents except methanol + ethyl acetate, the solubility values of MT had a positive relationship with the mass fraction of co-solvents. In methanol + ethyl acetate, the solubility of MT initially increased, followed by a decrease (with the rising mass fraction of methanol) and arrived the highest solubility value at a mass fraction of methanol being 0.4000. The Hansen solubility parameters (HSPs) were applied to study the solubility behaviors of MT in tested solvents. Moreover, in three pure solvents, the measured solubility data of MT was correlated by (NRTL-SAC, NRTL, two-Suffix Margules, UNIQUAC models and modified Apelblat equation). In binary solvents, the solubility data was fitted by (three-Suffix Margules, λh equation, Yaws model equation and modified Apelblat equation). Furthermore, the apparent thermodynamic properties were calculated based on the van’t Hoff equation. The positive values of apparent standard dissolution enthalpy and entropy suggest that the dissolution process of MT in all of chosen solvents is entropy-driven and endothermic. The larger values of ζH than ζTS represent that the main contributor of ΔdisGo in all investigated solvents is enthalpy.

Effect of cathode end plate on passive direct methanol fuel cell performance

Direct methanol fuel cell (DMFC) belongs to the class of fuel cells that use polymer electrolyte membrane and operate on methanol-water mixture. The low overall performance of passive DMFC compared to active DMFC is due to the slow anode reaction combined with inefficient cathode reaction. In this work, an attempt was made to augment the passive DMFC performance by modifying the structural design of the cathode end plate (CEP). The passive DMFC was fabricated and the performance was investigated experimentally. Three different CEP duct configurations were studied using 1 to 5 M methanol mass fraction. The results indicated higher performance for square duct CEP configuration, with 5 M methanol mixture.

Determination and correlation of solubility and solution thermodynamics of 4-aminobenzenesulfonamide in five binary solvent mixtures from 278.15 to 318.15 K

The solubility of 4-aminobenzenesulfonamide in five binary solvent systems, including methanol + toluene, ethanol + toluene, methanol + chloroform, ethanol + chloroform and methanol + ethanol under ambient pressure was measured using a gravimetric method at temperatures ranging from 278.15 to 318.15 K. The results illustrated that solubility of 4-aminobenzenesulfonamide in pure methanol is highest whereas that in chloroform is lowest in all tested solvents and solvent mixtures. In methanol containing mixed solvent systems, the solubility of 4-aminobenzenesulfonamide is just increased with increasing mass fraction of methanol whereas in ethanol containing systems the solubility of solute increased with increasing mass fraction of ethanol. The mole fraction solubility increases with increase in temperature in all pure and binary solvent systems. Five thermodynamic models, including modified Apelblat, Jouyban-Acree, van't Hoff- Jouyban-Acree, Apelblat- Jouyban-Acree and Wilson equations are selected to correlate the experimental solubility data in mixed solvents whereas modified Apelblat, van't Hoff and λh models used for pure solvents. All the results from fitted values indicate that those thermodynamic models were satisfactory agreement with experimental solubility results. The mixing thermodynamic properties of 4-aminobenzenesulfonamide in five binary solvents including Gibbs energy of mixing, enthalpy of mixing and entropy of mixing, reduced excess enthalpy (H1E, ∞ ), activity coefficients γ1and γ1∞ were calculated based on the Wilson model and thermodynamic relations.

Experimental Measurements and Correlation of Liquid Extraction of o-Xylene from Octane Using Mixed Solvents Including Dimethyl Sulfoxide and Methanol at 298.15 K

The purpose of the present work is to study the effect of adding different mass quantities of a light alcohol (methanol) to dimethyl sulfoxide, in order to extract o-xylene from octane. Experimental liquid–liquid equilibrium data for the quaternary systems {octane + o-xylene + dimethyl sulfoxide + (0.2, 0.4, 0.6, and 0.8) mass fraction of methanol} were determined at T = 298.15 K under atmospheric pressure. For the four quaternary systems, the selectivity and distribution coefficient of o-xylene were applied to assess the efficacy of (dimethyl sulfoxide + mass fraction of methanol) as mixed solvents. The triangular phase diagrams for all studied systems were sketched. The Non Random Two-Liquid activity coefficient model was employed to correlate experimental results and fitting parameters were reported.

5-Nitrosalicylaldehyde in aqueous co-solvent mixtures of methanol, ethanol, isopropanol and acetonitrile: Solubility determination, solvent effect and preferential solvation analysis

The equilibrium 5-nitrosalicylaldehyde solubility in methanol (1) + water (2), ethanol (1) + water (2), isopropanol (1) + water (2) and acetonitrile (1) + water (2) mixtures was determined by a shake-flask method from 273.15 K to 313.15 K under local pressure of 101.2 kPa. At the same mass fraction of methanol (ethanol, isopropanol or acetonitrile) and temperature, the mole fraction solubility of 5-nitrosalicylaldehyde was greater in (acetonitrile + water) mixture than in ethanol (1) + water (2), isopropanol (1) + water (2) and methanol (1) + water (2) mixtures. The relative importance of solute–solvent and solvent–solvent interactions upon the solubility variation was valued by using the linear solvation energy relationship analysis of solvent effect. The method of inverse Kirkwood–Buff integrals was used to study the preferential solvation on the basis of thermodynamic solution properties. The preferential solvation parameters for methanol, ethanol, isopropanol and acetonitrile were positive in the four mixtures in co-solvent-rich and intermediate composition, indicating that 5-nitrosalicylaldehyde was solvated preferentially by the co-solvent. It is conjecturable that in these regions 5-nitrosalicylaldehyde acts as a Lewis acid with the alcohols’ molecules; while for the acetonitrile + water mixture, the preferential solvation could be attributed to polarization effects. Moreover, the drugs’ solubility was mathematically represented via the Jouyban-Acree model acquiring the average relative deviations<6.03%.

Solubility of 4-Chloro-2,5-dimethoxynitrobenzene, 4-Chloro-2,5-dimethoxyaniline, and 2,5-Dimethoxyaniline in Binary and Pure Solvents: Determination and Modeling

Using the dynamic method over the temperature range of (277 to 340) K at atmosphere pressure, solubility of 4-chloro-2,5-dimethoxynitrobenzene (CDMB) and 4-chloro-2,5-dimethoxyaniline (CDMA) in methanol–water and ethanol–water solvent mixtures, where solute-free mass fraction of methanol and ethanol range from 0.2 to 0.8, and solubility of CDMB, CDMA, and 2,5-dimethoxyaniline (DMAn) in 2-methoxyethanol, 2-ethoxyethanol, 1-methoxy-2-propanol, and diethylene glycol have been investigated. In all solvents, there exists a direct relationship between solubility and temperature. In mixture solvents, the experimental data are correlated using the Wilson and the NRTL models. The solubility of CDMB and CDMA increases with the added amount of methanol or ethanol. In pure organic solvents, significant differences are discerned for the solubility of CDMB, CDMA, and DMAn, and data are correlated with the Wilson, the NRTL, the modified Apelblat, and the λh models. The solubility of DMAn is strongly dependent on tempera...

The dissolution behaviour and apparent thermodynamic analysis of diprophylline in pure and mixed solvents

Co-solvent plays an important role in drug crystallization. More importantly, the change of temperature and the addition of co-solvent can make the operation of crystallization purification more controllable. In this work, the solubility of diprophylline in methanol, ethanol, n-propanol, isopropanol, acetone, acetonitrile, ethyl acetate, 1,4-dioxane, water, toluene and mixture of (methanol + water) was experimentally determined at T = 283.15–323.15 K. The solubility data obtained experimentally in all studied pure solvents followed the sequence: water > 1,4-dioxane > methanol > acetonitrile > isopropanol > ethanol > n-propanol > ethyl acetate > toluene > acetone. In addition, in mixture of (methanol + water) the solubility increases at first and then decreases with the increasing mass fraction of methanol. The composition dependence of the solubility has a maximum around (methanol mass fraction) w = 0.4 at all investigated temperatures. Moreover, the effect of solvent properties on solubility is briefly discussed. The modified Apelblat equation, λh equation, Jouyban-Acree model and CNIBS/R-K model are applied to correlate the solubility. All the values of RAD and RMSD are no more than 5.34 × 10−2 and 5.83 × 10−4, respectively. Apparent thermodynamic analysis indicates that the dissolution is an endothermic and entropy driven process.

A comparative study on methanol/diesel and methanol/PODE dual fuel RCCI combustion in an automotive diesel engine

In the present work, an attempt was made to study and compare the effect of Methanol/Diesel and Methanol/PODE RCCI combustion in a 3-cylinder, turbocharged, CRDI, diesel engine. The test engine was suitably modified to use dual fuels by incorporating methanol port fuel injection system and an open electronic control unit. Experiments have been conducted at 3.4 bar BMEP and 1500 rpm by varying methanol premixed mass fraction at a constant CA50 of about 10°CA aTDC. The results show that increasing methanol mass fraction prolonged the ignition delay, decreased the in-cylinder pressure for both Methanol/Diesel and Methanol/PODE RCCI operation. At a premixed mass fraction of 80%, the maximum brake thermal efficiency of both Methanol/Diesel and Methanol/PODE is about 31% which is 3.5% higher than the conventional diesel combustion. Brake specific oxides of nitrogen and soot emissions are significantly reduced for both dual fuel RCCI combustion with increased methanol mass fraction. However, Brake specific hydrocarbon and carbon monoxide emissions are slightly increased. At a constant premixed mass fraction, Methanol/PODE dual fuel RCCI combustion resulted in more BSNO emission than Methanol/Diesel RCCI combustion. However, lower BSHC, BSCO and soot emissions are observed with Methanol/PODE dual fuel RCCI combustion compared to Methanol/Diesel RCCI combustion.

Quantitative analysis of ethanol–methanol–water ternary solutions using Raman spectroscopy

Raman spectroscopy was used for rapid in-situ measurement of alcohols in ethanol-methanol-water ternary systems. Mass fractions of the individual components were determined using calibration curves for binary systems of ethanol-water, methanol-water, and ethanol-methanol. Calibration curves were constructed by calculating the ratio of the Raman peak intensity of a component and that of an external standard (acetonitrile). Assuming additivity of the spectra, simultaneous equations were written, and mass fractions of ethanol, methanol, and water in the ternary solutions were determined by solving the system of equations through calculating an inverse matrix. The relative errors between the mass fractions obtained from the Raman spectra and those obtained from mass measurements were <0.6%.

Synergistic effect of salts and methanol in thermodynamic inhibition of sII gas hydrates

In this work phase equilibrium conditions for structure II (sII) gas hydrates in systems containing a mixture of salts (NaCl, KCl, CaCl2, MgCl2) and methanol have been measured using a high-pressure cell. The concentration of salts in aqueous solution (model of reservoir water) was constant in all experiments and equal to 18 wt%. Phase equilibrium conditions were determined by the isochoric method for pressures ranging from 1 to 4.7 MPa and for mass fraction of methanol from 0 to 50 wt%. The experimental data were obtained for water + salts, water + methanol, and water + salts + methanol systems. From the results obtained, it follows that 20 wt% of methanol in distilled water (DW) gives the thermodynamic shift of the hydrate decomposition temperature close to the brine one. Mixtures of 10% methanol + brine and 20% methanol + brine significantly better reduce the equilibrium temperature of hydrate dissociation compared to samples with the similar total mass fraction of inhibitor (methanol) in water (30, 40 wt%). At the pressures of more than 4 MPa combination of 20 wt% methanol + brine provide the same thermodynamic inhibition as 50 wt% of methanol in water. Thus, the synergism of the methanol + salts mixtures in the thermodynamic inhibition of sII gas hydrates has been observed. Synergism manifested itself in a greater shift of equilibrium curves to lower temperatures and higher pressures compared to systems containing only one thermodynamic hydrate inhibitor (THI). The obtained results indicate the possibility of a significant reduction in the consumption of polar organic THI for gas hydrate prevention in deposits with highly mineralized brine. However, it is necessary to take into account the possible complications associated with the precipitation of salts from solutions of water – salt(s) – polar organic THI due to the possible limited mutual solubility of the components.