High-pressure Distillation Research Articles

Remarkable C2H4 separation at ambient condition with a chemically sturdy porous MOF through pore confinement

An alternate to energy intensive cryogenic high-pressure distillation process for the separation of ethylene from its gas mixture with ethane is highly appealing. In this contribution, a highly chemically robust microporous MOF named 1 (stable in water, boiling water, and pH = 2–11) has been employed for preferential ethylene sorption with excellent selectivity. The simulation study disclosed the selective pore confinement of ethylene through non-covalent interactions with the amine and carboxylate sites of the framework backbone. Column breakthrough study unveiled 15.2 and 24.8 L kg−1 ethylene production per cycle at 298 K for the 50:50 and 90:10 (v/v) C2H4/C2H6 mixture which places this MOF as one of the best physisorbent material for ethylene separation. Industrial applicability is tested in a hydrous environment (displaying unaltered performance) as well as its regenerability under vacuum or mild heating for successive cyclic operations.

Experimental study of the distillation mechanism during coinjection of flue gas and steam for heavy oil development

As an industrial waste gas, flue gas achieves a favorable performance in assisting steam to develop heavy oil, where steam distillation plays a crucial role. However, there are few studies of the physical changes in heavy oil and the distillation mechanism during flue gas-steam coinjection, which seriously inhibits flue gas applications in oil fields. Herein, the comparative steam and flue gas + steam distillation experiments (superheat of 120 °C) and flue gas + steam distillation experiments at three superheat levels (0 °C, 48 °C and 100 °C) were conducted using a high-temperature and high-pressure distillation kettle. The carbon number distribution of distillates during distillation and heavy oil properties before and after distillation were compared and analyzed. The results showed that the effect of flue gas on steam distillation was significant, and the flue gas + steam distillation yield reached 20.24%, which was 3.88% higher than that of pure steam. With increasing steam superheat during flue gas–steam coinjection, the carbon number distribution range of the distillates gradually expanded, the distillation yield gradually increased, and the flue gas + steam distillation yields under the three superheat levels were 13.5%, 15.49% and 16.59%, respectively. Compared to pure steam distillation levels, resin hydrocracking and allosterism in the flue gas + steam distillation process were intensified, the resin content decreased, and the saturate, aromatic and asphaltene contents increased. Moreover, the heat exchange and heat utilization rates between steam and crude oil were improved under the flue gas effect, and the upper limit of the distillate carbon number significantly increased. The research results are significant for further refining the mechanism of flue gas enhanced steam development of heavy oil.

The unexpected weirdness of rate-based simulation of some high-pressure column operations

Diffusion is the process by which molecules move. One way to model multicomponent diffusion is with a version of Fick’s law: (J) = - [D] d(c)/dz where [D] is a matrix of multicomponent diffusion coefficients. [D] is the product of two other matrices, one of which involves partial derivatives of the fugacity or activity coefficients. It is usually the case that all of the elements on the main diagonal of [D] have a positive value. Wambui Mutoru and Firoozabadi (2011, 2012) showed that CO2-rich and N2-rich hydrocarbon systems could have main diagonal elements of [D] that are negative. Using rate-based column simulations, we have found that these negative main diffusion coefficients readily occur in some high-pressure distillation operations. We investigate these processes in more detail and explore the consequences for the design and operation of columns in which this phenomenon is predicted to occur.

Low-energy adsorptive separation by zeolites

Separation of mixture is always necessarily required in modern industry, especially in fine chemical, petrochemical, coal chemical and pharmaceutical industries. The challenge of the separation process is usually associated with small molecules with very similar physical and chemical properties. Among the separation techniques, the commonly used high-pressure cryogenic distillation process with combination of high pressure and very low temperature is heavily energy-consuming, which accounts for the major production costs as well as 10–15% of the world's energy consumption. To this end, the adsorptive separation process based on zeolite sorbents is a promising lower-energy alternative and the performance is directly determined by the zeolite sorbents. In this review, we surveyed the separation mechanisms based on the steric, equilibrium, kinetic and ‘trapdoor’ effect, and summarized the recent advances in adsorptive separation via zeolites including CO2, light olefins, C8 aromatics and hydrogen isotopes. Furthermore, we provided the perspectives on the rational design of zeolite sorbents for the absolute separation of mixtures.

Effect of pressure on thermo-oxidative reactions of saturates, aromatics, and resins (S-Ar-R) from extra-heavy crude oil

This work investigates the thermo-oxidative behaviour of saturates, aromatics, and resins, at different pressures of 0.084, 3.0, and 6.0 MPa. Saturates (S), aromatics (Ar), and resins (R) were characterized by elemental analysis, vapor pressure osmometry, 1H- and 13C-nuclear magnetic resonance, and X-ray photoelectron spectroscopy. The atmospheric evaporation of S, Ar, and R was evaluated by simulated distillation, whereas high-pressure distillation curves were created by calculation using the Clapeyron equation with the Redlich Kwong equation of state. The mass change and rate of mass change profiles were assessed in a high-pressure thermogravimetric analyzer (HP-TGA) by injecting nitrogen and air to obtain the pyrolysis and oxidation responses. Kinetic analysis was performed using a first-order kinetic model discretizing thermal oxidation profiles in four different regions, namely, oxygen chemisorption (OC), decomposition of chemisorbed oxygen-based compounds (DCO), first combustion (FC), and second combustion (SC). As main results, it was obtained that the saturates were just described by FC and SC regions at all pressures, while aromatics and resins by the four stages (OC, DCO, FC, and SC) for pressures higher than 3.0 MPa. At 6.0 MPa, aromatics exhibit a rapid consumption in the FC region, while resins present a more controlled consumption, distributed in the three decomposition regions. This implies that as pressure increases, aromatics have a greater influence on oxidation reactions at high temperatures. From pyrolysis curves, it was noted that the amount of coke generated follows the increasing order saturates < aromatics < resins for all pressures used. The kinetic parameters corroborated the results obtained. For the higher chemisorption systems, the effective activation energy values ​​were higher, and therefore the DCO values. At the same time, the pre-exponential factor showed opposite results given slower reaction kinetics in these stages.

Conversion of carbonyl compounds in bio-oil during the acid/base-catalysed reactive distillation at high pressure

The carbonyl compounds are mainly responsible for the instability and corrosiveness of a bio-oil. To upgrade or utilise a bio-oil, it is important to stabilise the carbonyl compounds. This study mainly investigates the conversion of carbonyl compounds in bio-oil via high-pressure reactive distillation in the presence of acid and base catalysts. It is found that high pressure could affect the distribution of carbonyl compounds in the bio-oil to accelerate the reaction of light carbonyl compounds and inhibit the reaction of heavy carbonyl compounds. The acid could not remove the carbonyl compounds significantly because it can not only catalyse the aldol condensation of carbonyl compounds but also help produce more carbonyl compounds by accelerating the hydrolysis of sugar compounds. The base (e.g. NaOH) could remove carbonyl compounds by acting as a catalyst to the aldol condensation reaction of aldehydes and ketones and neutralising the carboxylic acids during the high-pressure reactive distillation. Even though the based-catalysed aldol condensation could lead to the increase of the average molecular weight, the average boiling point of the distillation product is still in the acceptable range for fuels.

Enrichment of aromatic compounds during the high-pressure reactive distillation of bio-oil

The bio-oil produced from the renewable biomass is a sustainable source of aromatic compounds. The aromatic compounds in bio-oil would generally contribute to the coke formation during its further processing, which is a bottleneck problem for its further application due to the complex composition of bio-oil. In this study, the distribution and reaction of aromatic compounds during the high-pressure reactive distillation of bio-oil are investigated to achieve the enrichment of aromatic compounds to the distillate fraction. It is found that pressure could help transfer aromatic compounds into the distillate fraction. In addition, the increase of pressure could contribute to the reduction of polymerisation and the production of aromatic monomers due to the hydrothermal environment. Besides the process parameters, methanol could also be used to inhibit the polymerisation of aromatic compounds. Furthermore, the transfer of aromatic compounds could also be intensified using Ca(OH)2 based on the acidity of phenolic compounds.

C2s/C1 hydrocarbon separation: The major step towards natural gas purification by metal-organic frameworks (MOFs)

• This review will offer the importance of challenging C 2s /C 1 separation by MOFs. • Organization and summarization of more than a hundred examples have been made. • An in-depth critical discussion on this topic has been provided. • The key issues and future prospects are also discussed in detail. • Appealing review to the wider scientific communities, including their industry partners. Gas separation processes have significant impacts on human society’s current needs, starting from industrial, environmental, energy to high-value chemical necessities. Natural gas (NG) is used in various sectors across the globe and accounted to 32% of U.S. total primary energy consumption in 2019. Raw NG consisting primarily of C 1 hydrocarbon (CH 4 ) possesses a significant amount of C 2 hydrocarbons (5–9%) which needs to be removed and considered as the major step of NG processing. The high cost associated with the cryogenic high-pressure distillation process for the separation of C 2s /C 1 hydrocarbons from NG restricts its widespread usage. Porous metal-organic frameworks (MOFs), offer remarkable promise for such C 2s /C 1 hydrocarbon separations because of their easy tunability, functionality, and designability. Around a hundred of MOFs have been designed and synthesized for the potential applications in C 2s /C 1 hydrocarbon separations. Such reports are increasing swiftly and thus demands a summarization for at a glance visualization. In this review, we intend to showcase the development of MOFs with the superiority over other developed porous materials for such separation. We have described the strategies taken to obtain the trade-off between C 2s sorption capacity and separation selectivity of C 2s /C 1 . Furthermore, the challenges and future prospects are discussed elaborately.

Reactions and Distribution of Levoglucosan during the High-Pressure Reactive Distillation of Bio-Oil

High-pressure reactive distillation is a new bio-oil upgrading technology that can achieve high yields of the distillate due to reduced polymerization. Levoglucosan, as an anhydrous sugar, is one of the major components of bio-oil from the pyrolysis of biomass. To understand the reactive distillation of bio-oil at high pressure, the reactions and distribution of levoglucosan during the high-pressure reactive distillation of bio-oil were investigated in this study. Our results indicate that levoglucosan would mainly undergo hydrolysis during the high-pressure distillation, whereas thermal polymerization would dominate during the atmospheric pressure distillation. The reaction environment plays an important role in the levoglucosan reaction. The increase in pressure, temperature, water, and acetic acid concentration could accelerate levoglucosan conversion during bio-oil distillation, especially via the hydrolysis reaction. Most of the levoglucosan during the high-pressure reactive distillation could be converted into small molecules and distilled out due to the presence of light components retained in the liquid phase by high pressure. However, during the atmospheric pressure distillation, most of the levoglucosan would be mainly retained in the heavy residue to undergo polymerization reactions.

High-pressure reactive distillation of bio-oil for reduced polymerisation

The upgrading of bio-oil with the existing distillation technologies is mainly hindered by polymerisation due to the reactive nature of bio-oil when it is heated up during distillation. We propose that the distillation of bio-oil at high pressure can significantly reduce the extent of polymerisation. This study aims to investigate the roles of process parameters, especially pressure, in the high-pressure reactive distillation of bio-oil produced from the pyrolysis of mallee woody biomass. The bio-oil distillation fraction yields and properties were evaluated to demonstrate the advantages of the distillation at elevated pressures over distillation at atmospheric pressure. Our results indicate that high-pressure distillation can achieve high distillate yields with reduced polymerisation because high pressure can retain water and other light components in the liquid phase to reduce the extent of polymerisation. Besides reducing the polymerisation, high pressure could also intensify the separation during the flash separation step. The distillate yield was around 90% when the distillation was carried out at 200 °C at a pressure higher than 20 barg.

A "Thermodynamically Stable" 2D Nickel Metal-Organic Framework over a Wide pH Range with Scalable Preparation for Efficient C2 s over C1 Hydrocarbon Separations.

The design and construction of "thermodynamically stable" metal-organic frameworks (MOFs) that can survive in liquid water, boiling water, and acidic/basic solutions over a wide pH range is highly desirable for many practical applications, especially adsorption-based gas separations with obvious scalable preparations. Herein, a new thermodynamically stable Ni MOF, {[Ni(L)(1,4-NDC)(H2 O)2 ]}n (IITKGP-20; L=4,4'-azobispyridine; 1,4-NDC=1,4-naphthalene dicarboxylic acid; IITKGP stands for the Indian Institute of Technology Kharagpur), has been designed that displays moderate porosity with a BET surface area of 218 m2 g-1 and micropores along the [10-1] direction. As an alternative to a cost-intensive, cryogenic, high-pressure distillation process for the separation of hydrocarbons, MOFs have recently shown promise for such separations. Thus, towards an application standpoint, this MOF exhibits a higher uptake of C2 hydrocarbons over that of C1 hydrocarbon under ambient conditions, with one of the highest selectivities based on the ideal adsorbed solution theory (IAST) method. A combination of two strategies (the presence of stronger metal-N coordination of the spacer and the hydrophobicity of the aromatic moiety of the organic ligand) possibly makes the framework highly robust, even stable in boiling water and over a wide range of pH 2-10, and represents the first example of a thermodynamically stable MOF displaying a 2D structural network. Moreover, this material is easily scalable by heating the reaction mixture at reflux overnight. Because such separations are performed in the presence of water vapor and acidic gases, there is a great need to explore thermodynamically stable MOFs that retain not only structural integrity, but also the porosity of the frameworks.

Novel cryogenic argon recovery from the air separation unit integrated with LNG regasification and CO2 transcritical power cycle

Two novel air separation units at cryogenic temperature were proposed to reach high purity nitrogen, oxygen, and argon. The first process refers to a three-column cryogenic air separation plant without using an external refrigeration system. An integrated process including cryogenic air separation, combined-cycle power plants (e.g., transcritical CO2 cycle and gas turbine), and LNG regasification was presented and analyzed as the second process to produce liquid oxygen and vaporize LNG without using external refrigeration source. Results of the first proposed process demonstrate that the specific energy consumption of high purity nitrogen, oxygen, and argon reduces to 18.7%, 13%, and 12% respectively when compared with the conventional processes. Specific energy consumptions and exergy efficiency for the second plant improved by nearly 33% and 16% in comparison with the first process. Also, the gas turbine and CO2 power cycle efficiencies were almost 35% and 45% in the second process. Exergy analysis on both systems demonstrated that expansion valve V-2 (99.42%), high-pressure distillation columns (99.41%), and argon recovery section (98.34%) have the lowest irreversibility and highest exergy efficiency. Meanwhile, the highest exergy destructions in the first and second proposed plants belong to the low-pressure distillation tower of the first process and the combustion chamber of the second process with around 3400 kW and 24,000 kW respectively.

High-pressure cryogenic distillation data for improved LNG production

Current methods and models to reliably simulate and predict cryogenic column performance, essential for designing and operating commercial Liquefied Natural Gas (LNG) distillation and scrub columns, are currently lacking accurate and reliable empirical data at industrially-relevant conditions (high pressure/low temperature). This leads to conservative design for safety purposes. This paper endeavours to address this gap. Through the use of a unique cryogenic distillation column, critical experimental data at industry-relevant conditions (up to 4 MPa and down to 233 K) have been collected. This constitutes an essential step towards future optimization of LNG scrub columns, eliminating the requirement for over-design, thus improving production and reducing costs. The experimental data were compared with the predictions of the steady state model and showed reasonable agreement, although discrepancies were observed, confirming the need to improve models of LNG scrub columns.

Azeotropic pressure swing distillation of hydrochloric-water for hydrogen production in the Cu[sbnd]Cl cycle: Thermodynamic and design methods

A pressure swing distillation (PSD) process is designed and analyzed in this paper for the maximum boiling azeotrope separation of an HCl-water binary mixture to recycle concentrated HCl (aq) within the CuCl cycle of thermochemical hydrogen production. Aspen Plus simulation and EES software are used to evaluate the characteristics of the PSD apparatus in terms of flow streams, thermodynamic properties and compositions in the binary azeotropic mixture. A heat transfer and mass transfer analysis (with the McCabe-Thiele method) are also used to predict the height of the packed bed distillation column. Results indicate that both analyses predict the same values for the low and high pressure packing column height of 1.7 m and 2 m, respectively. Due to the component's volatility changes through the azeotropic transition at the HCl-water separation, the minimum and maximum concentration of the HCl (aq) would be at the distillate ports of low and high pressure columns, respectively. Moreover, to break the azeotropic point of HCl (aq) in the PSD system, the minimum required low pressure feed concentration at the operating line slopes of 0.2, 0.4, 0.6 and 0.8 should be 0.086, 0.092, 0.097 and 0.103, respectively. From the results, the re-boiler and condenser heat duties at the high pressure distillation column are more affected with the change in the slope of the operating line, compared to the low pressure side.

Thermodynamic model of pressure swing distillation for a high pressure process of hydrochloric/water separation and hydrogen production

Recycling of concentrated HCl within the CuCl cycle for hydrogen production is necessary to achieve lower operating costs and higher efficiency. HCl and water molecules have an attraction that leads to a maximum boiling azeotrope. Thus, HCl cannot be separated from water by using a conventional distillation column. In this paper, a novel thermodynamic model and simulations in Aspen Plus are presented for a pressure swing distillation high-pressure process to separate the HCl-water azeotropic binary mixture into a concentrated HCl stream. Furthermore, a heat transfer analysis is presented to predict the packing column height. All of the stream properties and compositions in the binary azeotropic mixture, thermodynamic analysis and steady-state simulation of a high pressure distillation column are examined with Aspen Plus. The present results indicate that the high-pressure distillation system enhances the mole fraction of HCl (aq) from 0.11 up to 0.21 and the increase of reflux ratio and feed temperature assist it to be higher. The increment of 76% and 42% for the condensation and re-boiler heat duties with the growth of reflux ratio indicate the significant impact of this parameter on the high pressure distillation column. Furthermore, at the specific system operating condition, the results from the heat transfer model suggest that the distillation column with a height of 2 m would be suitable for practical operation.

Thermodynamic modelling of VLE behaviour at the high purification of R717 refrigerant by high-pressure batch distillation

The feasibility of using thermodynamic simulation models for describing the VLE behaviour of dilute ammonia-impurity solutions during high purification of R717 refrigerant by distillation is discussed. A comprehensive evaluation of different thermodynamic models (EoS-, LACT-based, combined EoS-LACT, predictive) has been done by comparing the simulation results with published experimental VLE data for ammonia-based dilute solutions in the pressure/temperature range from the boiling point of ammonia up to the critical point. The behaviour of the three important impurity groups (permanent gases, hydrocarbons, and water) in high-purity ammonia is considered in the dilute region. The studied systems are characterised by non-ideality, combine components from different chemical classes and with different polarity, contain subcritical and supercritical components, and can form associates in liquid and vapour phase. The results show that, depending on the system and the operating pressure, various modelling approaches can be successfully employed in the simulation of distillation-based separations involving VLE of non-ideal highly diluted ammonia-based mixtures. Equally important is the type of mixing rules, as well as the quality of the binary interaction parameters used in the relations. The usage of some of the predictive methods is shown to be a sensible option for a preliminary design.

Optimized distillation coupled with state-of-the-art membranes for propylene purification

The growing production of polyolefins, mainly polyethylene and polypropylene, currently demands increasing outputs of polymer-grade light olefins. The most commonly adopted process for the separation of olefin/paraffin mixtures is performed by energy intensive high pressure or cryogenic distillation, which is considered the most expensive operation in the petrochemical industry. The use of membrane technology offers a compact and modular solution for capital and energy savings, thanks to process intensification. In this work, we move one step forward in the design of hybrid propane/propylene separation systems, using computer aided modeling tools to identify economically optimal combinations of distillation and state-of-the-art membranes. A model is proposed to optimize a hybrid configuration, whereby the membrane performs the bulk separation and the distillation column is intended for the final product polishing, accounting for membrane investment cost and process operating expenses. The decision variables are the membrane area and the column reflux ratio, and the model is able to calculate the optimal feed trays. The upper-bound properties of selected membranes, which define their performance and reliability criteria, have been studied, benchmarking the economic evaluation against conventional distillation in order to assess the expedience of a hybrid system implementation.

5-21 圧縮成形によるバイオマスボードの作成と針葉油及び心材成分の高圧水蒸気蒸留法の開発(Session 5 バイオマス)

5-21 圧縮成形によるバイオマスボードの作成と針葉油及び心材成分の高圧水蒸気蒸留法の開発(Session 5 バイオマス)

Hydrodynamic feasibility of the production of biodiesel fuel in a high-pressure reactive distillation column

Among the different processes for producing biodiesel fuel, the use of methanol under conditions near to the critical point is a promissory alternative. The reactive distillation has been proposed to reduce the energy requirements of the esterification step in this process. Such reductions are accompanied by reductions in the total annual costs and the environmental impact. However, due to the conditions under which the column should be operated, special care must be taken in the design of the trays and their hydraulic performance. Proper design of the trays should prevent operational problems. In this work, a strategy for the mechanical design of sieve trays in a homogeneous reactive distillation column is presented. In the column, oleic acid is esterified with methanol under a pressure of 7MPa. The designs obtained are tested in terms of hydraulics through CFD simulations. CFD analysis is carried out using ANSYS Fluent software.

An improved back-flush-to-vent gas chromatographic method for determination of trace permanent gases and carbon dioxide in ultra-high purity ammonia

A novel method for rapid, quantitative determination of trace permanent gases and carbon dioxide in ultra-high purity ammonia by dual-channel two-dimensional GC-PDHID is presented. An improved matrix back-flush-to-vent approach combining back-flush column switching technique with auxiliary NaHSO4 ammonia trap is described. The NaHSO4 trap prevents traces of ammonia from entering the analytical column and is shown not to affect the impurity content of the sample. The approach allows shortening the analysis time and increasing the amount of measurements without extensive maintenance of the GC-system. The performance of the configuration has been evaluated utilizing ammonia- and helium-based calibration standards. The method has been applied for the analysis of 99.9999+% ammonia purified by high-pressure distillation at the production site.