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Zeolites are widely employed in the industrial drying of gases by Temperature Swing Adsorption (TSA). In a typical TSA process, the adsorbent is packed in a fixed bed, which is sequentially subjected to a “cold” feed (adsorption) and a hot flush (desorption). Due to the hydrothermal stress, adsorbents may suffer from reduced drying capacity in long-term service. The aim of this work is to assess the impact of thermal aging of two zeolite materials (LTA and CHA) having similar pore openings but different Si/Al ratios. We examined how simulated thermal aging affected porous texture, coke deposition and water vapor adsorption equilibrium and kinetics. Both zeolites showed reduced uptake of probe molecules (N2 at 77 K and CO2 at 273 K) and water vapor (303 K) when subjected to simulated thermal aging. In Fourier-Transform Infrared Spectroscopy (FTIR) analyses, only the aged LTA zeolite showed bands related to the presence of aromatic compounds. Water vapor adsorption uptake decreased 28.6% and 18.4% for LTA and CHA at 30 mbar, respectively. Kinetic studies indicate a reduction in water diffusion coefficient after the aging cycles. Although LTA has a significantly higher affinity for water as compared to CHA, the latter is much more resistant to hydrothermal aging with comparatively faster water diffusion.

Two types of zeolites (type X and type A) were synthesized from fly ash of two Brazilian coal based power plants via hydrothermal treatment after ash fusion with NaOH. The synthesized zeolites were characterized by means of XRF, XRD, SEM and gas adsorption (N2 and CO2 adsorption/desorption at − 196 and 0 °C, respectively). Pure CO2 and N2 adsorption equilibrium isotherms were performed at 50, 70 and 90 °C to measure the CO2 adsorption capacity and selectivity of CO2 over N2. CO2/N2 binary isotherms (15/85% v/v) were also obtained at the same temperatures. Commercial zeolitic materials used for CO2/N2 separation such as zeolite 13X and zeolite 4A underwent the same characterization and adsorption measurements as benchmarks to evaluate the performance of the synthesized zeolites. The synthesized materials from fly ash are promising low cost adsorbents for CO2 separation, reaching ca. 83% of the CO2 adsorption capacity of their commercial counterparts at 0.15 bar and 50 °C.

In this study, two configurations of Temperature Swing Adsorption (TSA) were assessed with the aim of evaluating their efficacy on CO2 capture on commercial adsorbent zeolite 13X within a post-combustion scenario. A fixed bed setup was employed to measure breakthrough curves from the adsorption and desorption steps. Considering a dry desulfurized flue gas stream, breakthrough curves for CO2–N2 (15/75 % v/v) in Helium were performed at 25, 50 and 75 °C. The desorption step was carried out following two TSA regeneration strategies: a two-step desorption arrangement (configuration 1) consisting of a purging phase followed by a heating-purging phase, and a one-step desorption arrangement (configuration 2) involving only the heating-purging phase. Adsorption equilibrium isotherms were also obtained for pure CO2 (25, 50, 75, 100 and 125 °C) and N2 (25, 50 and 75 °C) on zeolite 13X in the range of 0–1 bar. Finally, a mathematical model considering mass and energy differential balances was used to predict the whole adsorption-desorption history. The results obtained on breakthrough curves showed that CO2 separation from N2 on zeolite 13X is accomplished by adsorption under the studied conditions with a marked selectivity for CO2. In regards to the desorption phase, configuration 1 may not be adequate for an integration of adsorption-desorption steps once only the purge phase duplicates the desorption time as compared to the adsorption stage. On the other hand, configuration 2 is more likely to synchronize the whole adsorption—desorption process since the regeneration time was significantly reduced by this strategy. However, configuration 1 managed to obtain full CO2 recovery with all the temperatures tested during the heating step, whereas configuration 2 reached recovery values around 92%. Moderate temperatures (e.g. 125–150 °C) are feasible to be used for configuration 2 regeneration strategy so as to avoid energy penalties. Simulations were able to reproduce well the experimental breakthrough curves, even though some discrepancies were observed in the desorption histories.

Mesoporous silica SBA-15 solids have been synthesized at different aging temperature with the goal of obtaining materials with different textural properties. The synthesized samples have been evaluated for their CO2 adsorption capacity. In order to increase the CO2 adsorption capacity and the CO2/N2 selectivity, the SBA-15 synthesized at different aging temperatures were functionalized via grafting with 3-aminopropyltriethoxysilane (APTES) and via impregnation with polyethyleniminethylenediamine branched (PEI) or tetraethylenepentamine (TEPA). In all cases, the adsorption isotherms of the amine functionalized silica are fitted to the Dualsite-Langmuir model, where physical and chemical adsorption sites are reported. The isotherms reveal that grafted-silicas with APTES displayed the coexistence of both adsorption sites, while the adsorption process of PEI or TEPA impregnated-silicas are mainly governed by chemical interactions. The adsorption isotherms show that the most promising adsorbent for CO2 capture in terms of CO2 adsorption capacity and CO2/N2 selectivity is the SBA synthesized at 393 K (aging temperature) and functionalized with TEPA (50 wt%) (SBA-393-50T). This sample reached a CO2 adsorption capacity of 2.83 mmol g−1 at 100 kPa and 338 K. The CO2 adsorption capacity of this material decreased around 5% after the first adsorption/desorption cycle, maintaining a constant value for successive cycles. SBA-393-50T also showed an outstanding CO2/N2 selectivity, increasing significantly as the CO2 concentration decreases.

In view of the promising applicability of adsorption to the capture of CO2 from post-combustion gases, the use of mesoporous silica functionalized with 3-aminopropyltriethoxysilane (APTES) was studied as adsorbent in a fixed bed for CO2–N2 separation under thermal swings. Characterization of the adsorbent performed before and after functionalization indicated that amine grafting was successful. Additionally, CO2 adsorption on a magnetic suspension balance showed a significant increase in uptake of the APTES-functionalized sample over the support, mainly at low relative pressures. Relatively high values of adsorption enthalpy suggest the occurrence of chemical adsorption attributed to CO2 bonding with the amines. Breakthrough curves were measured for pure CO2, N2 and the CO2/N2 (15/75% v/v) mixture, which showed good agreement with respect to the uptake of the individual gases, as determined from gravimetric tests. Full CO2 desorption from the bed required a temperature rise, which suggests that these materials may be suitable for TSA cyclic processes. A temperature of 90 °C was enough for a complete regeneration of the adsorbent during the desorption phase under dynamic conditions. The material showed very stable behavior after 20 successive cycles.

In this work, amine-grafted mesoporous silica were investigated using a adsorption microcalorimetry and supplementary techniques in order to study the influence of increasing the density of grafted amine on the CO2 binding mechanisms. A Tian–Calvet microcalorimeter coupled to a manometric setup was used to evaluate the energetic heterogeneity of adsorption sites and to calculate the thermokinetic parameter from the differential enthalpy curves. With such device, equilibrium adsorption isotherms of CO2 were simultaneously measured at 25 °C for all samples up to 1 bar. The adsorption microcalorimetric study suggests a change in active sites distribution as the density of grafted amines increases. The maximum thermokinetic parameter of 471 s for the pure silica support at 30.7 kJ mol−1 suggests that physisorption is the dominant binding mechanism. A different behavior occurs with the grafted samples: they have considerably higher enthalpy values corresponding to the formation of reacted species on the surface (chemisorbed CO2), which depend on grafted amine density and available free surface silanols. Kinetics of formation of chemisorption products, together with hindered CO2 diffusion, seriously impair the approach to equilibrium, which leads to a decrease in uptake upon isothermal pressure-swing cycles at low temperatures (25 °C). CO2 could be successfully desorbed at 120 °C from the sample with highest uptake (MSG60), which showed a constant uptake for three adsorption–desorption cycles using only vacuum at 50 °C.

The water present in all gas stream leads to changes in the adsorbed amount of the target gas and the selectivity among the constituents of the mixture. The high stability characteristics and low cost of the new Al(OH) fumarate MOF synthetized by BASF, makes it an interesting porous material with mild hydrophobic properties for industrial use. Thus, new force field parameters were proposed for the CO2, N2 and CH4 /Al(OH) fumarate systems validated by adsorption experimental data in three temperatures. The sittings of CO2, N2, CH4 and H2O molecules inside the MOF pores at high (303 K) and low (150 K or 230 K) temperatures were also presented. An alternative approach that performed Monte Carlo simulations on two ensembles, the canonical ensemble (NVT) and the grand canonical ensemble (µVT), was validated and applied to evaluate the coadsorption of CO2/H2O, N2/H2O and CH4/H2O for a MOF exposure to the relative humidity of 14, 20, 25, 30 and 40% at 303 K. The gases molecules fill the center of the pores of the Al(OH) fumarate MOF near the aluminum clusters. The water molecules showed a complex behavior, forming clusters even in the early stages of adsorption. The Al(OH)-fumarate MOF, when compared to NaX, shows hydrophobic behavior and impaired in CO2 capacity only at relative humidity above 20%. We also found that CO2 selectivity increases for CO2/N2 and CO2/CH4 as the amount of water increases. We hope that the proposed methodology to study water coadsorption could be applied to other frameworks to assist in the screening of MOF for separation/capture.

In this work, solid wastes from the flocculation step of a drinking water treatment plant were used as starting material to obtain CO2 adsorbents upon thermal treatment and a pillaring strategy. Thermally treated solid waste and pillared materials were characterized by XRD, FTIR, TGA, N2 adsorption–desorption isotherms at 77 K, XPS and elemental analysis. From the characterization results, it was found that the introduction of silica pillars was successful, leading to heterostructured materials with higher specific surface area and pore volume. In order to improve the CO2 adsorption capacity, pillared materials were functionalized by grafting with (3-aminopropyl)triethoxysilane (APTES)and impregnation with polyethylenimine (PEI). Pillared materials could be loaded with up to 50 wt% PEI. PEI-impregnated pillared adsorbents were tested for CO2 adsorption at 298 and 348 K and CO2/N2 adsorption at 348 K using a Magnetic Suspension Balance equipped with a mixture gas dosing (Rubotherm, Germany). Langmuir and Sips models were used to fit monocomponent and mixture experimental data, considering two different sites for CO2 adsorption. At 1 bar, 50PEI-SiFe (loaded with 50 wt% PEI) adsorbed 2.5 and 3.6 mmol CO2 g−1 at 298 and 348 K, respectively and exhibited an extremely high CO2/N2 selectivity (above 150 mol CO2/mol N2 at 348 K). Nevertheless, PEI loaded adsorbents still exhibit a lower amine efficiency as compared to APTES-grafted counterparts, due to diffusion restrictions caused by the high viscosity of the impregnated polymer.

In this paper we discuss why the pore geometry can affect the unicity of the pore size distribution (PSD) of a given activated carbon (AC) sample, when different probe gases are used in adsorption measures. In order to characterize the solid sample we used grand canonical Monte Carlo simulation and the independent pore model with slit or triangular pore geometry, focusing our analysis on the possibility of representing the adsorptive processes of a triangular pore of defined size by means of a combination of slit pores of different sizes. This representation is tested on experimental adsorption data of N2 (77 K) on AC samples and acceptable results were obtained. Finally, we have performed a theoretical test, which consisted of analyzing a virtual porous solid with this approach and different probe gases (N2 at 77 K and CO2 at 273 K), showing that the differences between the pore representations can cause differences between the solid representations for the adsorptive properties, for these different gases. The analysis presented here can be extended to other pore geometries and other adsorbates, and provide arguments to further explain results presented in our previous paper, which refers to cases when different adsorbates yield different PSDs for a given sample and the same pore geometry model. Fil: Toso, Juan Pablo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - San Luis. Instituto de Física Aplicada ; Argentina. Universidad Nacional de San Luis. Facultad de Ciencias Físico Matemáticas y Naturales. Departamento de Física; Argentina Fil: Cornette, Valeria Cecilia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - San Luis. Instituto de Física Aplicada ; Argentina. Universidad Nacional de San Luis. Facultad de Ciencias Físico Matemáticas y Naturales. Departamento de Física; Argentina Fil: Yelpo, Victor Antonio. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - San Luis. Instituto de Física Aplicada ; Argentina. Universidad Nacional de San Luis. Facultad de Ciencias Físico Matemáticas y Naturales. Departamento de Física; Argentina Fil: Alexandre de Oliveira, José Carlos. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - San Luis. Instituto de Física Aplicada ; Argentina. Universidade Estadual do Ceará; Brasil Fil: Azevedo, D.C.S.. Universidade Estadual do Ceará; Brasil Fil: López, Raúl Horacio. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - San Luis. Instituto de Física Aplicada ; Argentina. Universidad Nacional de San Luis. Facultad de Ciencias Físico Matemáticas y Naturales. Departamento de Física; Argentina

Ion-exchange with different cations (Na+, NH4 +, Li+, Ba2+ and Fe3+) was performed in binderless 13X zeolite pellets. Original and cation-exchanged samples were characterized by thermogravimetric analysis coupled with mass spectrometry (inert atmosphere), X-ray powder diffraction and N2 adsorption/desorption isotherms at 77 K. Despite the presence of other cations than Na (as revealed in TG-MS), crystalline structure and textural properties were not significantly altered upon ion-exchange. Single component equilibrium adsorption isotherms of carbon dioxide (CO2) and methane (CH4) were measured for all samples up to 10 bar at 298 and 348 K using a magnetic suspension balance. All of these isotherms are type Ia and maximum adsorption capacities decrease in the order Li > Na > NH4–Ba > Fe for CO2 and NH4–Na > Li > Ba for CH4. In addition to that, equilibrium adsorption data were measured for CO2/CH4 mixtures for representative compositions of biogas (50 % each gas, in vol.) and natural gas (30 %/70 %, in vol.) in order to assess CO2 selectivity in such scenarios. The application of the Extended Sips Model for samples BaX and NaX led to an overall better agreement with experimental data of binary gas adsorption as compared to the Extended Langmuir Model. Fresh sample LiX show promise to be a better adsorption than NaX for pressure swing separation (CO2/CH4), due to its higher working capacity, selectivity and lower adsorption enthalpy. Nevertheless, cation stability for both this samples and NH4X should be further investigated.

In this work we have studied the CO2 adsorption capacity and CO2/CH4 separation on several APTES-grafted mesoporous silicas of SBA-15 type. The synthesis was modified in order to obtain pore expanded materials, and post synthesis functionalization was carried out by grafting with APTES (by immersion in 20 % v/v solution). The samples were characterized by elemental (CNH) analysis, X-ray diffraction, N2 adsorption–desorption isotherms at −196 °C, and TGA. To test the CO2 adsorption capacity and CO2/CH4 separation of all samples, a gravimetric method with a magnetic suspension balance (Rubotherm, Germany) was used. Monocomponent and mixture adsorption isotherms were measured at 25 °C. All isotherms were recorded to 10 bar. Monocomponent experimental data were fitted to Langmuir and Dual-site Langmuir models and the mixture experimental data were well fitted to Multiregion Extended Langmuir combined with Dualsite Langmuir model, achieving a good correlation between experimental and simulated data.

The aim of this work was to evaluate the ability of Cibacron Blue F-3GA dye-ligand chitosan/alginate epoxide on human IgG adsorption under different buffer systems at 25 mmol L−1: Morpholinoethane sulfonic acid, morpholinopropane sulfonic acid, hydroxyethylpiperazine ethanesulfonic acid and tris-hydroxymethyl aminomethane (Tris–HCl). Batch adsorption studies were performed in order to evaluate the effect of buffer pH and nature on IgG uptake as well the equilibrium isotherms. Chromatographic experiments were performed with both human IgG (high purity) and human serum and each buffer with NaCl 1.0 M was used in the elution step. Best results (maximum equilibrium adsorption capacity of 110.9 mg g−1) were found at pH 7.8 with Tris–HCl buffer. The Langmuir–Freundlich model provided a good fit for the adsorption isotherm. In chromatographic experiments with high purity IgG and Tris/HCl buffer, IgG dynamic adsorption capacity onto E-Ch/Al-Cibacron was 13.4 mg g−1, which accounted for 60 % of IgG injected into the column. Chromatographic experiments with diluted (tenfold) human serum were conducted and it was found by electrophoresis that IgG is preferentially adsorbed with respect to other proteins using all buffers systems, especially with Tris–HCl. The amount of desorbed protein from E-Ch/Al-Cibacron was around 7.0 mg g−1 for all buffers. The new stationary phase showed high affinity for IgG and may be a potential adsorbent for human IgG purification.

in this work, the characterization of Activated Carbons (AC) by using the independent pore models is discussed, with special emphasis on the issue of how the assumed pore geometry can affect the resulting Pore Size Distribution (rPSD) and on the problem of the unicity of the PSD when different probe molecules are used in adsorption experiments. A theoretical test was performed using virtual solids based in the so-called Mixed Geometry Model (MGM) (Azevedo et al. 2010). The MGM uses a kernel of adsorption isotherms generated by GCMC for different pore sizes and two pore geometries: slit and triangular. The adsorption isotherms of a virtual MGM solid were fitted with both the traditional Slit Geometry Model (SGM) and the Mixed Geometry Model (MGM). It is demonstrated that, by assuming a different pore geometry model from that of the real sample, different PSDs may be obtained by fitting adsorption isotherms of different probe gases. Finally, experimental results are shown which both point toward the MGM as an acceptable extension of the SGM and confirm that the MGM is a closer representation of the actual porous structure of most activated carbons. Fil: Toso, Juan Pablo. Universidad Nacional de San Luis. Facultad de Cs.fisico Matematicas y Naturales. Departamento de Fisica; Argentina Fil: Alexandre de Oliveira, José Carlos. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico San Luis. Instituto de Física Aplicada; Argentina Fil: Soares Maia, Debora Aline. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico San Luis. Instituto de Física Aplicada; Argentina Fil: Cornette, Valeria Cecilia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico San Luis. Instituto de Física Aplicada; Argentina Fil: López, Raúl Horacio. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico San Luis. Instituto de Física Aplicada; Argentina Fil: Azevedo, D. C. S.. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico San Luis. Instituto de Física Aplicada; Argentina. Universidade Federal do Ceará; Brasil Fil: Zgrablich, Jorge Andres. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico San Luis. Instituto de Física Aplicada; Argentina

The adsorption of naphthalene and pyrene on two different types of commercial activated carbons was stud- ied by batch and column experiments. Adsorption equilib- rium was measured at three different temperatures. Heats of adsorption were estimated from the equilibrium results and compared to other previous reports. From the column experiments, using parameters obtained from the batch ex- periments and literature correlations, effective surface diffu- sivities were estimated for naphthalene and pyrene on both adsorbents in different feed concentrations. The corrected diffusivities, using Darken equation, appear to be almost constant for naphthalene (ca. 1.3 · 10 −8 cm 2 /min), and for pyrene (ca. 2.3 · 10 −10 cm 2 /min), in both activated carbons.

Adsorption may be a potentially attractive alternative to capturing CO2 from stationary sources in the context of Carbon Capture and Sequestration (CCS) technologies. Activated carbon and zeolites are state-of-art adsorbents which may be used for CO2 adsorption, however physisorption alone tends to be insignificant at high temperatures. In the present work, commercial adsorbents have been impregnated with monoethanolamine (MEA) and triethanolamine (TEA) in order to investigate the effect of the modified surface chemistry on CO2 adsorption, especially above room temperature. Adsorption isotherms for CO2, N2 and CH4 were measured in a gravimetrically system in the pressure range of UHV to 10 bar, at 298 and 348 K for activated carbon and zeolite 13X supports. The adsorbed concentration of CO2 was significantly higher than those of CH4 and N2 for both adsorbents in the whole pressure range studied, zeolite 13X showing a remarkable affinity for CO2 at very low pressures. However, at 348 K, the adsorbed concentration of CO2 decreases significantly. The supports impregnated with concentrated amine solutions and dried in air suffered a detrimental effect on the textural properties, although CO2 uptake became much less susceptible to temperature increase. Impregnations carried out with dilute solution followed by drying in inert atmosphere yielded materials with very similar textural characteristics as compared to the parent support. CO2 isotherms in such materials showed a significant change with similar capacities at 348 K as compared to the original support at 298 K in the case of activated carbons. The impregnated zeolite showed a decrease in adsorbed phase concentration in low pressures for a given temperature, but the adsorbed amount also seemed to be less affected by temperature. These results are promising and indicate that CO2 adsorption may be enhanced despite high process temperatures (e.g. 348 K), if convenient impregnation and drying methods are applied.

A headspace technique, that consists in analyzing the composition of the vapor phase in equilibrium with the condensed phase of a mixture in a sealed vial containing the adsorbent sample, has been recently applied to acquire equilibrium data for adsorption of xylenes in liquid phase. In this study, we used this technique to measure experimental binary equilibrium data for C8 aromatics in Y and mordenite zeolitic molecular sieves. For the Y zeolite, we also measured C8 aromatics quaternary equilibrium data. Measurements were made at temperatures between C 40–80 °C. A more tedious, but traditional, chromatographic pulses method was also used to validate some of the results.

The diffusion behavior of C4–C10n-alkanes in silicalite-1 has been investigated by using the Zero Length Column method. The diffusivities derived from measurements at different purge rates with different purge gases confirming intracrystalline diffusion control. Data are compared with results reported in the literature for MFI zeolites. The diffusivities were found to be consistent and agree well with data previous obtained by ZLC. However, these data showed a remarkable disagreement with other reported techniques (PFG-NMR, QENS and Permeation). The eventual influence of carbon dioxide (CO2) adsorption on diffusion properties of n-alkanes in silicalite was also investigated. For this purpose, a series of experiments was performed involving hydrocarbons mixed with CO2. Data were obtained at 303 K and flow rates between 20 and 80 mL/min. The presence of CO2 does not seem to influence the intracrystalline transport rate of the investigated light hydrocarbons (n-C4 and n-C6). On the other hand, the situation for n-C8 and n-C10 is more complex. The diffusivity values are higher compared to the previously reported values.

Activated carbon samples from coconut shells (Brazilian coconut species “Coco da Baia”) were prepared by chemical activation with phosphoric acid as the activating agent. Samples were characterized by nitrogen adsorption isotherms at 77 K. Some samples were randomly chosen in order to perform methane adsorption experiments under pressures between 1 and 60 bar at 303 K. A close relationship between surface area, micropore volume and methane adsorption capacity for carbons prepared from the same starting material was observed. The highest methane storage capacity in the tested samples was found to be 95 v/v at 303 K and 35 bar, which is comparable to results obtained for commercial samples indicated for this application. A moderate concentration of phosphoric acid (around 35%) seems to favor high surface areas, micropore volumes and, hence, gas storage capacity. The inclusion of an acid wash step before carbonization and the use of inert gas flow during carbonization also seem to enhance the development of porosity. This result suggests that activated carbons prepared from “Coco da Baia” by chemical activation with phosphoric acid have potential to be used as a storage media for natural gas.

This paper presents an experimental and theoretical study of the adsorption equilibria of methane on activated carbon, focusing on the accurate determination of the absolute adsorbed mass from raw gravimetric measurements performed at high pressures (above 0.1 MPa). Two carbon samples were selected for these studies: a commercial sample (SRD-21) and a sample prepared in laboratory from coconut shells (CAQF-30). A gravimetric set up was used to measure the adsorption properties. Methane isotherms were obtained in the pressure range of 1 to 70 bar and under temperatures from 10 to 80∘C. Equilibrium experimental data were evaluated with the aid of three approaches labeled as D, DD and DDA, the latter being proposed for the first time in this paper. The DDA approach provided consistent and physically meaningful results for the adsorbed phase density. The adsorption isotherm that was obtained following the DDA approach matched those obtained following an approach published in the literature. The results indicate that the CAQF-30 sample, despite being prepared from carbonaceous wastes, presents competitive values for the methane adsorption parameters when compared to the commercial sample.

This study presents experimental data of storage and delivery tests of methane on activated carbon carried out in a prototype vessel at pressures up to 40 atm. Adsorption equilibrium data at high pressure were measured using a gravimetric apparatus. Experimental data obtained from the storage/delivery tests are compared to those obtained from process simulation using a dynamic model. The simulation model was run using the measured equilibrium data as input parameters. A good agreement was observed between experimental and simulated results. Histories of pressure and stored mass were satisfactorily well predicted. Despite heat effects, not precisely taken into account in the model, there was a reasonably good agreement between simulation and experiment for the average temperature inside the vessel.

This paper presents experimental results for equilibrium and diffusion of C8 aromatics in laboratory synthesised crystals of AlPO4-11. The samples were prepared by the hydrothermal method, starting from pseudobohemite (CONDEA), 85% phosphoric acid, water and di-isopropilamine as organic template. Adsorption and diffusion data were obtained mainly by gravimetry at temperatures between 60–100°C. Saturation capacities were found in the range of 4 wt%. Equilibrium constants were estimated using virial plots yielding heats of adsorption between 10–12 Kcal/mol at low coverage. Intracrystalline diffusivities at higher temperatures (150–180°C) were also measured, using the Zero-Length-Column (ZLC) method. Diffusivities from both methods (gravimetric and ZLC) agreed reasonably well and followed a typical Arrhenius behaviour, with low activation energy (ca. 7 Kcal/mol).