Kinetic Selectivity Research Articles

Chemical tools for epichaperome-mediated interactome dysfunctions of the central nervous system

Diseases are a manifestation of how thousands of proteins interact. In several diseases, such as cancer and Alzheimer’s disease, proteome-wide disturbances in protein-protein interactions are caused by alterations to chaperome scaffolds termed epichaperomes. Epichaperome-directed chemical probes may be useful for detecting and reversing defective chaperomes. Here we provide structural, biochemical, and functional insights into the discovery of epichaperome probes, with a focus on their use in central nervous system diseases. We demonstrate on-target activity and kinetic selectivity of a radiolabeled epichaperome probe in both cells and mice, together with a proof-of-principle in human patients in an exploratory single group assignment diagnostic study (ClinicalTrials.gov Identifier: NCT03371420). The clinical study is designed to determine the pharmacokinetic parameters and the incidence of adverse events in patients receiving a single microdose of the radiolabeled probe administered by intravenous injection. In sum, we introduce a discovery platform for brain-directed chemical probes that specifically modulate epichaperomes and provide proof-of-principle applications in their use in the detection, quantification, and modulation of the target in complex biological systems.

The production of hydro‐processed renewable diesel over the nonsulfide catalyst

In this study, the main process involves the conversion of palm oil into hydro-processed renewable diesel (HRD) over a nonsulfide catalyst. First, catalysts with different supports (γ-Al2O3 and SAPO-11) and metals (Ni and Mo) are compared in experiments. The results showed that 8Ni-8Mo/γAl2O3 is the most suitable catalyst for HRD production, with the highest conversion and selectivity of 99.5% and 98.9%, respectively. The chemical kinetic reaction, conversion, and selectivity of the catalyst were analyzed through different temperatures, pressures, and H2-to-oil ratios to determine the optimal conditions. The regenerated catalyst through calcining showed well recovered structure and textural properties by using X-ray diffraction, thermal gravimetric analysis, Fourier transfer infrared spectroscopy, and N2 adsorption/desorption measurements. Last but not least, the fuel components and properties of HRD were determined, include 46.8 MJ/kg of heating value, distillation temperature of 306°C, 5°C of cloud point, 81.4 of cetane number, 204°C of auto-ignition temperature, 62°C of flash point, and 61.8 mm of smoke point, which meets the diesel specifications.

Kinetic Selection in the Out‐of‐Equilibrium Autocatalytic Reaction Networks that Produce Macrocyclic Peptides

AbstractAutocatalytic reaction networks are instrumental for validating scenarios for the emergence of life on Earth and for synthesizing life de novo. Here, we demonstrate that dimeric thioesters of tripeptides with the general structure (Cys‐Xxx‐Gly‐SEt)2 form strongly interconnected autocatalytic reaction networks that predominantly generate macrocyclic peptides up to 69 amino acids long. Some macrocycles of 6–12 amino acids were isolated from the product pool and were characterized by NMR spectroscopy and single‐crystal X‐ray analysis. We studied the autocatalytic formation of macrocycles in a flow reactor in the presence of acrylamide, whose conjugate addition to thiols served as a model “removal” reaction. These results indicate that even not template‐assisted autocatalytic production combined with competing removal of molecular species in an open compartment could be a feasible route for selecting functional molecules during the pre‐Darwinian stages of molecular evolution.

Kinetic Selection in the Out-of-Equilibrium Autocatalytic Reaction Networks that Produce Macrocyclic Peptides.

Autocatalytic reaction networks are instrumental for validating scenarios for the emergence of life on Earth and for synthesizing life de novo. Here, we demonstrate that dimeric thioesters of tripeptides with the general structure (Cys-Xxx-Gly-SEt)2 form strongly interconnected autocatalytic reaction networks that predominantly generate macrocyclic peptides up to 69 amino acids long. Some macrocycles of 6-12 amino acids were isolated from the product pool and were characterized by NMR spectroscopy and single-crystal X-ray analysis. We studied the autocatalytic formation of macrocycles in a flow reactor in the presence of acrylamide, whose conjugate addition to thiols served as a model "removal" reaction. These results indicate that even not template-assisted autocatalytic production combined with competing removal of molecular species in an open compartment could be a feasible route for selecting functional molecules during the pre-Darwinian stages of molecular evolution.

Computational design of penicillin acylase variants with improved kinetic selectivity for the enzymatic synthesis of cefazolin

Enzymatic synthesis plays a pivotal role in the sustainable production of semi-synthetic β-lactam antibiotics. However, these types of green syntheses are being developed slowly because of a lack of appropriate enzymes. In the present work, a computational strategy was developed to identify variants of penicillin G acylase that can catalyze the condensation between methyl 1H-tetrazol-1-yl acetate (TZAM) and 7-amino-3-[(5-methyl-1,3,4-thiadiazol-2-yl) thiomethyl] cephalosphoranic acid (7-ZACA) to produce cefazolin in a fully aqueous medium. An initial library containing 770 sequences was generated by our computational enzyme design program PRODA, which applied a deterministic global minimization algorithm to optimize the binding between the acyl donor and the attacking nucleophile for high kinetic selectivity. The 13 top-ranked variants were subjected to experimental testing based on evaluation by multiple short-time molecular dynamics simulations. A single variant (R145αG) was experimentally confirmed to afford higher kinetic selectivity with a synthesis/hydrolysis ratio (S/H) that was increased by approximately 40% compared with the wild type, and the immobilized enzyme catalyst gave a yield of cefazolin of up to 92% with a 1.8:1 molar ratio of TZAM/7-ZACA, which to our knowledge is the lowest molar ratio of TZAM/7-ZACA to produce a yield over 90%. This study represents considerable progress toward cefazolin synthesis under practical conditions and indicates that this computational strategy could improve enzyme properties for the bio-manufacturing of non-natural molecules.

Confined Crystallization of Polymers within Nanopores

Crystallization of polymeric materials under nanoscopic confinement is highly relevant for nanotechnology applications. When a polymer is confined within rigid nanoporous anodic aluminum oxide (AAO) templates, the crystallization behavior experiences dramatic changes as the pore size is reduced, including nucleation mechanism, crystal orientation, crystallization kinetics, and polymorphic transition, etc. As an experimental prerequisite, exhaustive cleaning procedures after infiltrations of polymers in AAO pores must be performed to ensure producing an ensemble of isolated polymer-filled nanopores. Layers of residual polymers on the AAO surface percolate nanopores and lead to the so-called "fractionated crystallization", i.e., multiple crystallization peaks during cooling.Because the density of isolated nanopores in a typical AAO template exceeds the density of heterogeneities in bulk polymers, the majority of nanopores will be heterogeneity-free. This means that the nucleation will proceed by surface or homogeneous nucleation. As a consequence, a very large supercooling is necessary for crystallization, and its kinetics is reduced to a first-order process that is dominated by nucleation. Self-nucleation is a powerful method to exponentially increase nucleation density. However, when the diameter of the nanopores is lower than a critical value, confinement prevents the possibility to self-nucleate the material.Because of the anisotropic nature of AAO pores, polymer crystals inside AAO also exhibit anisotropy, which is determined by thermodynamic stability and kinetic selection rules. For low molecular weight poly(ethylene oxide) (PEO) with extended chain crystals, the orientation of polymer crystals changes from the "chain perpendicular to" to the "chain parallel to" the AAO pore axis, when the diameter of AAO decreases to the contour length of the PEO, indicating the effect of thermodynamic stability. When the thermodynamic requirement is satisfied, the orientation is determined by kinetics including crystal growth direction, nucleation, and crystal growth rate. An orientation diagram has been established for the PEO/AAO system, considering the cooling condition and pore size.The interfacial polymer layer has different physical properties as compared to the bulk. In poly(l-lactic acid), the relationship between the segmental mobility of the interfacial layer and crystallization rate is established. For the investigation of polymorphic transition of poly(butane-1), the results indicate that a 12 nm interfacial layer hinders the transition of Form II to Form I. Block and random copolymers have also been infiltrated into AAO nanopores, and their crystallization behavior is analogously affected as pore size is reduced.

Toward a Multipathway Perspective: pH-Dependent Kinetic Selection of Competing Pathways and the Role of the Internal Glutamate in Cl-/H+ Antiporters.

Canonical descriptions of multistep biomolecular transformations generally follow a single-pathway viewpoint, with a series of transitions through intermediates converting reactants to products or repeating a conformational cycle. However, mounting evidence suggests that more complexity and pathway heterogeneity are mechanistically relevant due to the statistical distribution of multiple interconnected rate processes. Making sense of such pathway complexity remains a significant challenge. To better understand the role and relevance of pathway heterogeneity, we herein probe the chemical reaction network of a Cl-/H+ antiporter, ClC-ec1, and analyze reaction pathways using multiscale kinetic modeling (MKM). This approach allows us to describe the nature of the competing pathways and how they change as a function of pH. We reveal that although pH-dependent Cl-/H+ transport rates are largely regulated by the charge state of amino acid E148, the charge state of E203 determines relative contributions from coexisting pathways and can shift the flux pH-dependence. The selection of pathways via E203 explains how ionizable mutations (D/H/K/R) would impact the ClC-ec1 bioactivity from a kinetic perspective and lends further support to the indispensability of an internal glutamate in ClC antiporters. Our results demonstrate how quantifying the kinetic selection of competing pathways under varying conditions leads to a deeper understanding of the Cl-/H+ exchange mechanism and can suggest new approaches for mechanistic control.

Supercritical fluid chromatography using methacrylate-based monolithic column for the separation of polar analytes.

A poly(N,N-dimethyl-N-methacryloyloxyethyl-N-(3-sulfopropyl) ammonium betaine-co-ethylene dimethacrylate) monolith was prepared in a 100× 2.0mm id stainless-steel column and was investigated for supercritical fluid chromatography. Optimization of its porosity was performed by changing the conditions of polymerization. Then, the chemical group of this column was confirmed by Fourier transform infrared spectroscopy and elemental analysis. The morphology was characterized by scanning electron microscopy. The prepared column showed good repeatability based on the retention factor of adenine, uracil and cytosine to calculate their run-to-run, day-to-day, column-to-column, and batch-to-batch relative standard deviations. Those values were less than 1.9% (n=10), 6.5% (n=3), 5.6% (n=3), and 1.7% (n=3), respectively. In addition, the column was found to be stable within 3 and 10 days with relative standard deviations less than 6.5 and 8.5%, respectively. These results indicated that the columns showed good reproducibility and stability. Compared with liquid chromatogaphy, supercritical fluid chromatography provided better kinetic performance and selectivity. Finally, several neutral, acid, and basic polar analytes were utilized to test its application. The results demonstrated that the prepared column exhibited a good separation performance and showed great potential in supercritical fluid chromatography.

Removal of textile dyes by benefited marine shells wastes: From circular economy to multi-phenomenological modeling

Marine shell wastes were thermally activated and characterized as aragonite and calcite phases and were used in the removal of synthetic anionic dyes, Bright Blue Acid (NB180) and Reactive Red 133 (RR133). Benefited marine shells were classified as low-cost (USD 0.33/g of adsorbent) in comparison with other reported materials. Furthermore, the absence of chemicals in the adsorbent preparation allows its further employment in economic activities. The coexistence of adsorption and exchange-precipitation reaction was responsible for up to 93% of dye removal, whilst the maximum adsorption capacities were 225 mg g−1 for NB180 and 36 mg g−1 for RR133. The observed kinetic behavior of the dye removal by the adsorbent allowed the proposal of a mechanism for dye-adsorbent interaction in liquid-solid interface considering both adsorption and exchange-precipitation reaction. Contribution of the exchange-precipitation reaction in the removal process was quantified as being approximately 75% for NB180 and 25% for RR133. The mathematical model that phenomenologically described the kinetic behavior of the dye removals gave the magnitude order of the kinetic parameters as kads = 8.67–9.49 min−1 and kp = 1.18–2.84 min−1, due to the adsorption and the (exchange-reaction)-precipitation, respectively. This work indicates the step (exchange reaction)-precipitation as an additional contribution to improve the dye removal from aqueous effluents, achieving in the evolution of the process up to 24% in terms of kinetic selectivity of removal.

Abstract 295: Implementing fully automated kinase inhibitor characterization using a robotic system

Abstract About 50 kinase inhibitors have been approved by the FDA for different indications so far. On the way from target validation to approval, the biochemical characterisation of a novel kinase inhibitor is a challenging, yet absolutely critical task. High resolution, kinetic molecular profiling can enable better data-driven decision making early on in the drug discovery process, not only saving time and resources, but also leading to superior molecular design. Arctoris developed a robotics-enabled process for fully automated kinase inhibitor characterisation, providing an unparalleled depth of data capture, going beyond the current state-of-the-art of biochemical assay setup. We validated our technology platform establishing assays against four members of the Janus Kinase family (JAK1, JAK2, JAK3, TYK2), profiling a set of JAK inhibitors. Of note, several JAK inhibitors with prior FDA approval for other indications entered clinical trials for COVID-19 treatment, making this target class particularly relevant for an in-depth study. Reagent validation, assay development, calibration, and optimization were expedited through systematic multifactorial experimental design, high density assay plate formats and versatile automated liquid handling. The Arctoris Ulysses platform affords 9 orders of magnitude range in liquid volume handling, with picolitre precision and contact-free digital dispensing for true, non-serial, independent experimentation. Fully automated protocols were optimized, validated, versioned, and explicitly encoded. Robust potency measurements of all inhibitors were established against each of the JAK targets, revealing molecules with distinct isoform selectivity. Designing and selecting molecules with specific activity profiles enables the fine tuning of pharmacology and the avoidance of unwanted off-target toxicity. Our unique platform, assay design, and deep expertise enabled the identification of molecules within the JAK inhibitor set that exhibit a range of kinetic properties. Our mechanistic analyses can help to elucidate the mode of inhibition (competitive, allosteric, synergistic etc.) as well as provide information pertaining to the kinetic selectivity that may be present but missed by focusing solely on potency. Citation Format: Daniel A. Thomas, Tom A. Fleming, Martin-Immanuel Bittner. Implementing fully automated kinase inhibitor characterization using a robotic system [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 295.

Efficient separation of propylene and propane on SAPO-17 molecular sieve

In this study, the separation performance of propylene and propane on SAPO-17 molecular sieve was investigated by static and dynamic adsorption. The adsorbent possessed good regeneration behavior because the strong adsorption of propylene at room temperature was eliminated by ion exchange treatment. Dynamic adsorption experiments revealed that the kinetic separation selectivity of propylene and propane was as high as 1980, which could be attributed to the energy barrier difference when diffusing through the eight-membered ring of SAPO-17 molecular sieve. The breakthrough experiments verified the good separation performance of the SAPO-17 adsorbent, which suggests that it has considerable application potential in propylene/propane separation.

Quantification and Prediction of Imine Formation Kinetics in Aqueous Solution by Microfluidic NMR Spectroscopy.

Quantitatively predicting the reactivity of dynamic covalent reaction is essential to understand and rationally design complex structures and reaction networks. Herein, the reactivity of aldehydes and amines in various rapid imine formation in aqueous solution by microfluidic NMR spectroscopy was quantified. Investigation of reaction kinetics allowed to quantify the forward rate constants k+ by an empirical equation, of which three independent parameters were introduced as reactivity parameters of aldehydes (SE , E) and amines (N). Furthermore, these reactivity parameters were successfully used to predict the unknown forward rate constants of imine formation. Finally, two competitive reaction networks were rationally designed based on the proposed reactivity parameters. Our work has demonstrated the capability of microfluidic NMR spectroscopy in quantifying the kinetics of label-free chemical reactions, especially rapid reactions that are complete in minutes.

Direct Dynamics Trajectories Reveal Nonstatistical Coordination Intermediates and Demonstrate that σ and π-Coordination Are Not Required for Rhenium(I)-Mediated Ethylene C-H Activation.

The C-H activation reaction between Cp(PMe3)2Re and ethylene results in kinetic selectivity for the Re-vinyl hydride I over the thermodynamically more stable Cp(PMe3)2Re(η2-ethylene) π-complex II. While transition-state and variational transition-state structures were located for individual pathways leading to I and II, DFT and CCSD(T) energies predict a large kinetic selectivity of 102-104, which is incompatible with the experimental 10:1 ratio. DFT direct quasiclassical trajectories revealed that the transition states do not provide a qualitatively correct reaction mechanism or a quantitatively correct selectivity due to a nonstatistical σ-CH coordination intermediate that precedes the transition states for C-H activation and π coordination. Using metadynamics and quasiclassical direct dynamics, we show that trajectories for the reaction between Cp(PMe3)2Re and ethylene result in direct formation of either the Re-vinyl hydride I or the π-complex II. Trajectories leading to the Re-vinyl hydride skip σ-coordination and do not require π-coordination. Consistent with experiments, trajectory selectivity provides a relatively small kinetic selectivity for the Re-vinyl hydride.

Exploiting Bidirectional Electrocatalysis by a Nanoconfined Enzyme Cascade to Drive and Control Enantioselective Reactions

The ability to drive and observe rapid enzyme catalysis in both directions is an important and natural consequence of immobilizing cascade components within electrode nanopores and coupling reactions to the fast, quasi-reversible NADP+/NADPH electrochemistry mediated by bound ferredoxin-NADP+ reductase. This approach has been exploited to investigate and control the redox interconversions between a ketone and secondary alcohol enantiomers catalyzed by enantioselective alcohol dehydrogenase variants. An anticipated advantage of the bidirectionality, in allowing a single cascade to be cycled back and forth while exploiting kinetic selectivity, was the ability to achieve a simple one-electrode de-racemizer; significantly, this was overturned because the nanoconfined enzyme system strongly directs racemization, the thermodynamic outcome. By modifying the concept, it was easily demonstrated that efficient one-pot de-racemizers can be achieved by using two electrodes in sequence, each containing an alcohol dehydrogenase that is enantioselective for one of the half-cycles.

Deconstruction of high-density polyethylene into liquid hydrocarbon fuels and lubricants by hydrogenolysis over Ru catalyst

Polyethylene (PE) is the most popular plastic globally, and the widespread use of plastics has created severe environmental issues. High energy consumption in the current process makes its recycling a challenging problem. In our report, the depolymerization of high-density PE was conducted in various liquid-phase solvents with the Ru/C catalyst under relatively mild conditions. The maximum yields of the jet-fuel- and lubricant-range hydrocarbons were 60.8 and 31.6 wt %, respectively. After optimization of the reaction conditions (220°C and 60 bar of H 2 ), the total yield of liquid hydrocarbon products reached approximately 90 wt % within only 1 h. The product distribution could be tuned by the H 2 partial pressure, the active-metal particle size, and the solvents. The solvation of PE in the different solvents determined the depolymerization reaction kinetics, which was confirmed by the molecular dynamics simulation results. • Ru/C was a highly active catalyst for the liquid-phase hydrogenolysis of HDPE • Solvent effects were prominent in the depolymerization of HDPE • H 2 partial pressure played a significant role in the HDPE depolymerization pathway • Total yield of liquid products reached around 90 wt % within 1 h at 220°C Plastic pollution has become one of the most pressing environmental issues now that the rapidly increased production of disposable plastic products is far beyond the world's capacity for recycling and upcycling waste plastics. Although recent studies have provided a few catalytic strategies for producing value-added fuel and chemical products from polyethylene (PE) waste, the kinetic rates and/or selectivities are unsatisfactory, even with extended processing time (24 h) and high temperatures (>280°C). This work reports a liquid-phase catalytic hydrogenolysis process that highly efficiently converts high-density PE to jet-fuel- and lubricant-range hydrocarbons under relatively mild conditions. The application of this efficient liquid-phase catalytic hydrogenolysis process could provide a promising approach for selectively producing high-value products, such as lubricants, from waste PE and other polyolefin polymers. Plastic pollution has become one of the most pressing environmental issues and needs to be tackled imminently. Here, Lin and coworkers report a liquid-phase catalytic hydrogenolysis process that highly efficiently converts high-density polyethylene (PE) to jet-fuel- and lubricant-range hydrocarbons under relatively mild conditions. Solvents profoundly affect the depolymerization reaction kinetics and product selectivity. This work provides a promising approach for selectively producing high-value products, such as jet fuel and lubricants, from waste PE and other polyolefin polymers.

A model selection framework to quantify microvascular liver function in gadoxetate‐enhanced MRI: Application to healthy liver, diseased tissue, and hepatocellular carcinoma

We introduce a novel, generalized tracer kinetic model selection framework to quantify microvascular characteristics of liver and tumor tissue in gadoxetate-enhanced dynamic contrast-enhanced MRI (DCE-MRI). Our framework includes a hierarchy of nested models, from which physiological parameters are derived in 2 regimes, corresponding to the active transport and free diffusion of gadoxetate. We use simulations to show the sensitivity of model selection and parameter estimation to temporal resolution, time-series duration, and noise. We apply the framework in 8 healthy volunteers (time-series duration up to 24 minutes) and 10 patients with hepatocellular carcinoma (6 minutes). The active transport regime is preferred in 98.6% of voxels in volunteers, 82.1% of patients' non-tumorous liver, and 32.2% of tumor voxels. Interpatient variations correspond to known co-morbidities. Simulations suggest both datasets have sufficient temporal resolution and signal-to-noise ratio, while patient data would be improved by using a time-series duration of at least 12 minutes. In patient data, gadoxetate exhibits different kinetics: (a) between liver and tumor regions and (b) within regions due to liver disease and/or tumor heterogeneity. Our generalized framework selects a physiological interpretation at each voxel, without preselecting a model for each region or duplicating time-consuming optimizations for models with identical functional forms.

Cyclotetrabenzoin Acetate: A Macrocyclic Porous Molecular Crystal for CO2 Separations by Pressure Swing Adsorption**

AbstractA porous molecular crystal (PMC) assembled by macrocyclic cyclotetrabenzoin acetate is an efficient adsorbent for CO2 separations. The 7.1×7.1 Å square pore of PMC and its ester C=O groups play important roles in improving its affinity for CO2 molecules. The benzene walls of macrocycle engage in an apparent [π⋅⋅⋅π] interaction with the molecule of CO2 at low pressure. In addition, the polar carbonyl groups pointing inward the square channels reduce the size of aperture to a 5.0×5.0 Å square, which offers kinetic selectivity for CO2 capture. The PMC features water tolerance and high structural stability under vacuum and various gas adsorption conditions, which are rare among intrinsically porous organic molecules. Most importantly, the moderate adsorbate‐adsorbent interaction allows the PMC to be readily regenerated, and therefore applied to pressure swing adsorption processes. The eluted N2 and CH4 are obtained with over 99.9 % and 99.8 % purity, respectively, and the separation performance is stable for 30 cycles. Coupled with its easy synthesis, cyclotetrabenzoin acetate is a promising adsorbent for CO2 separations from flue and natural gases.

Cyclotetrabenzoin Acetate: A Macrocyclic Porous Molecular Crystal for CO2 Separations by Pressure Swing Adsorption*.

A porous molecular crystal (PMC) assembled by macrocyclic cyclotetrabenzoin acetate is an efficient adsorbent for CO2 separations. The 7.1×7.1 Å square pore of PMC and its ester C=O groups play important roles in improving its affinity for CO2 molecules. The benzene walls of macrocycle engage in an apparent [π⋅⋅⋅π] interaction with the molecule of CO2 at low pressure. In addition, the polar carbonyl groups pointing inward the square channels reduce the size of aperture to a 5.0×5.0 Å square, which offers kinetic selectivity for CO2 capture. The PMC features water tolerance and high structural stability under vacuum and various gas adsorption conditions, which are rare among intrinsically porous organic molecules. Most importantly, the moderate adsorbate-adsorbent interaction allows the PMC to be readily regenerated, and therefore applied to pressure swing adsorption processes. The eluted N2 and CH4 are obtained with over 99.9 % and 99.8 % purity, respectively, and the separation performance is stable for 30 cycles. Coupled with its easy synthesis, cyclotetrabenzoin acetate is a promising adsorbent for CO2 separations from flue and natural gases.

Design and experiment of high-productivity two-stage vacuum pressure swing adsorption process for carbon capturing from dry flue gas

A two-stage vacuum pressure swing adsorption (VPSA) process that coupled kinetically controlled and equilibrium controlled separation process with reflux has been investigated for capturing carbon dioxide from dry flue gas (85% N 2 /15% CO 2 ). In the first enriching stage, carbon molecular sieve (CMS), which shows kinetic selectivity for CO 2 /N 2 , is adopted as the adsorbent to remove most N 2 in feed gas, thereby upgrading CO 2 and significantly reducing the amount for further refinement. The second stage loads zeolite 13X as adsorbent to purify the CO 2 -rich flow from the first stage for meeting the requirements of National Energy Technology Laboratory. Series of experiments have been conducted for adsorption isotherms measuring and lab-scale experimental validation as well as analysis. The effect of feed composition on the separation performance of the PSA system was studied experimentally and theoretically here. The optimal results achieved 95.1% purity and 92.9% recovery with a high CO 2 productivity (1.89 mol CO 2 ·h −1 ·kg −1 ) and an appropriate energy consumption of 1.07 MJ·(kg CO 2 ) −1 . Further analysis has been carried out by simulation for explicating the temperature, pressure, and concentration distribution at cyclic steady state.

ITQ-69: A Germanium-Containing Zeolite and its Synthesis, Structure Determination, and Adsorption Properties.

In this work, a new zeolite named as ITQ-69, has been synthesized, characterized and its application as selective adsorbent for industrially relevant light olefins/paraffins separations has been assessed. This material has been obtained as pure germania as well as silica-germania zeolites with different Si/Ge ratios using a diquaternary ammonium cation as organic structure directing agent. Its structure was determined by single-crystal X-Ray diffraction showing a triclinic unit cell forming a tridirectional small pore channel system (8×8×8R). Also, it has been found that Si preferentially occupies some special T sites of the structure as deduced from Rietveld analysis of the powder X-ray diffraction patterns. In addition, the new zeolite ITQ-69 has been found to be stable upon calcination and thus, its adsorption properties were evaluated, showing a promising kinetic selectivity for light olefin separations in the C3 fraction.