Molecular Basket Research Articles

Molecular baskets form inclusion complexes with phenethylamine drugs in water.

Molecular basket 16- comprising a nonpolar cavity and an anionic nest of six carboxylates at its rim was found to form inclusion complexes with (1R, 2S)-ephedrine, (1R, 2R)-pseudoephedrine, and (1S, 2R)-tranylcypromine. Experimental results (NMR) and theory (MM/DFT) suggest the basket encapsulates phenethylamines in unique and predictable fashion.

Developing High-Capacity Solid "Molecular Basket" Sorbents for Selective CO2 Capture and Separation.

ConspectusSince carbon-based energy continues to dominate (over 80%) the global primary energy supply, carbon dioxide capture, utilization, and sequestration (CCUS) is deemed to be a promising and viable option to mitigate greenhouse gas emissions and climate change, for which CO2 capture is critical to the overall success of CCUS. Although liquid amine scrubbing is a mature technology for carbon capture, it is energy-intensive and costly due to energy consumption in solvent heating and water evaporation apart from the energy needed to break amine-CO2 bonding. To address this challenge, Song's group developed a new design approach for adsorptive CO2 capture and separation, namely, "molecular basket" sorbents (MBS), without the need for dealing with solvent heating and water evaporation. The solid MBS consisting of polymeric amines (such as PEI) immobilized into nanoporous materials (such as SBA-15) possesses a high capacity for CO2 capture with high selectivity, fast kinetics, and good regenerability. Consequently, MBS can greatly reduce energy consumption and carbon capture cost. Conventional adsorbents such as zeolites, activated carbon, alumina, and silica have low adsorption capacities, and their use of CO2 adsorption requires prior removal of moisture and cooling of flue gas (∼35 °C). On the contrast, the CO2 sorption capacity of MBS can even be promoted by the presence of moisture/steam and reaches the best performance closer to flue gas temperature (∼75 °C). This Account presents an overview of our research progress in the material development and fundamental understanding of MBS for CO2 capture and the separation of CO2 from various gas streams. It begins with an illustration of the MBS concept, followed by efforts to improve the performance and pilot-scale demonstration of MBS for CO2 capture. With the systematic characterization of MBS by various ex situ and in situ techniques, a better understanding is developed for the CO2 sorption process mechanistically. Furthermore, this Account demonstrates how the fundamental understanding of the CO2 sorption mechanism promotes the further development of more robust and advanced sorbent materials with improved CO2 sorption capacity, kinetics of sorption and desorption, and cyclic stability. Finally, an outlook is provided for the future design and development of novel sorbent materials and the CO2 sorption process for various gas streams including flue gas, biogas, air, and hydrogen streams.

Vapor-Phase-Infiltrated AlOx/PIM-1 “Hybrid Scaffolds” as Solution-Processable Amine Supports for CO2 Adsorption

Energy-efficient adsorptive CO2 capture requires both adsorbent materials with high CO2 capacity and structured adsorption contactors possessing fast mass transfer kinetics and low pressure drop. The state-of-the-art research primarily focuses on “hard” adsorbents such as mesoporous zeolites and metal–organic frameworks, which exhibit high CO2 capacities but are challenging to translate into structured contactors. Polymer of intrinsic microporosity 1 (PIM-1), a solution-processable microporous polymer, is a “softer” alternative that can be easily fabricated into structured adsorption contactors. In prior research, PIM-1 has been utilized as a “molecular basket” for poly(ethylene imine) (PEI). Despite nanoscale amine dispersion and excellent processability, PEI/PIM-1 composites possess an unstable micropore structure, which collapses at high PEI loadings (∼30%) and results in lower CO2 adsorption capacity than PEI-loaded hard oxides. Here, we applied a post-fabrication polymer stabilization method, vapor phase infiltration (VPI), to improve the CO2 capacity of the PEI/PIM-1 composite without sacrificing its processibility. PIM-1 is fabricated into structured adsorption contactors and then reinforced with amorphous aluminum oxyhydroxide (AlOx) nanostrands via VPI. The resulting AlOx/PIM-1 is a stable, hierarchically porous support, which can be loaded with 40% PEI without pore collapse. Owing to the combination of processibility, comparable CO2 capacity, and high amine efficiency, PEI/AlOx/PIM-1 composites are a promising alternative to PEI-loaded mesoporous oxides.

Regenerable solid molecular basket sorbents for selective SO2 capture from CO2-rich gas streams

A series of molecular basket sorbents (MBSs) consisting of SBA-15 loaded with ethylene glycol (EG) derivatives and dimethyl sulfoxide (DMSO) are developed and investigated for sulfur dioxide (SO2) capture from industrial tail gas streams. The EG derivatives and DMSO are successfully immobilized on the support via surface interaction with the silanol groups as evidenced by DRIFTS analysis. The mesoporous structure of SBA-15 is preserved after loading with different compounds, with no major morphology changes. The SO2 sorption capacity increases with decreasing the molecular weight of EG derivatives. Furthermore, changing the terminal group of EG derivatives from hydroxyl (-OH) to methoxy (-OCH3) improves SO2 sorption capacity. DMSO-based MBS exhibits much higher SO2 affinity (64 mg-SO2/g-sorb.) than EG-based sorbents (<25 mg-SO2/g-sorb.). DMSO/SBA-15 sorbents are able to selectively capture SO2 in the presence of high CO2 concentration (30 %) with a relative selectivity factor of 120. Pre-saturating the DMSO-based sorbents with water vapor does not affect SO2 sorption capacity, and the sorbents possess good stability and regenerability. Moreover, the spent DMSO/SBA-15 sorbent could be further applied for H2S removal for producing elemental sulfur via Claus reaction between H2S and the adsorbed SO2, providing an environmentally friendly and sustainable way of regenerating the spent DMSO/SBA-15 sorbents.

Deep removal of SO2 from cathode air over polyethylenimine-modified SBA-15 sorbents for fuel cells

The performance and longevity of fuel cells can be significantly degraded by the contaminants in the air, such as SO2 and NO2, which poison the cathode catalysts. The cleanup of the cathode air in a real environment may thus be required. In this work, SO2 sorption and desorption behavior over molecular basket sorbents (MBSs) consisting of polyethylenimine (PEI) and SBA-15 has been studied. The effects of temperature, PEI loading and SO2 concentration on the sorption capacity of PEI-SBA-15 sorbents were examined. The results showed that the sorption temperature and PEI loading amount greatly influence the sorption performance. The regenerability study showed that only about 10–40 % of sorption capacity was recoverable over the spent PEI-SBA-15 sorbents due to the strong chemical interaction between SO2 and amine sites. Additionally, the influence of co-existing NO2 on SO2 sorption was examined, showing a competitive sorption between SO2 and NO2 over PEI-SBA-15 sorbent. The current study demonstrates that the PEI-BA-15 sorbent could be promising for deep removal of SO2 and NO2 from the cathode air for fuel cells.

Robust “dry amine” solid CO2 sorbent synthesized by a facile, cost-effective and environmental friendly pathway

The low cost and facile preparation of CO2 sorbents are extremely important for the practical CO2 capture application. In this study, we demonstrate a facile preparation of “dry amine” CO2 sorbents through a cost-effective and environmental friendly pathway. Commercially available mass-produced SiO2 nanoparticles were used as the support of “molecular basket” sorbents. Tetraethylenepentamine (TEPA) was quickly (60 s) loaded on the surface of SiO2 nanoparticles through high-speed mechanical mixing (22000 rpm) method. Compared with the conventional wet impregnation method, no solvent is required. Although this new pathway is simple, timesaving, cost-effective and environmental friendly, the prepared sorbents present excellent CO2 capture performance. The results show that with the increase of the TEPA loading, the CO2 adsorption amount of the TEPA/SiO2 sorbent increases first and then decreases. The 50TEPA/SiO2 sorbent shows much higher CO2 uptake (3.98 mmol/g) than SBA-15 based sorbent (2.45 mmol/g) prepared through the same method. And it also displays lower mass transfer resistance due to the small particle size and the open structure while 50TEPA/SBA-15 shows larger mass transfer resistance due to the channel structure. The results also show that 50TEPA/SiO2 has good reproducibility. Due to the low cost and facile preparation, the dry amine sorbents may also show the potential application for urgent use, such as SO2 leak or H2S leak.

Druggable fusion gene landscape in solid tumors.

e13517 Background: Kinases activated by gene fusions represent an important class of oncogenes in solid tumors highlighted by the unique site agnostic FDA approval of larotrectinib for NTRK gene rearrangements. However, the frequency and types of druggable fusions in solid tumors are not well characterized from the clinical perspective. Methods: Oncofocus is a clinically validated precision oncology platform that includes analysis of 399 druggable driver-partner oncogenic fusion genes linked to 140 unique targeted therapy protocols. A retrospective analysis of Oncofocus trending data in a real-life cohort of 1111 patients has been used to determine the actionable fusion gene landscape in solid tumors. Results: Eighty nine actionable fusion genes were identified in 1111 samples of solid tumors linked to 73 targeted therapy protocols. Seven of the samples harbored multiple fusion genes. Eighty two of the 1111 samples tested had at least one actionable fusion gene representing a frequency of 7.38%. The highest frequency of actionable fusions were observed in glioblastoma (23%), head and neck (12%), kidney (11%) and prostate (10%) cancers. Four of the seven samples with multiple actionable fusions were found in glioblastoma. Pancreatic, lung and endometrial cancers and cancer of unknown primary (CUPs) had an actionable fusion gene frequency ranging from 7-9%. TBL1XR1-PIK3CA, MET-MET, WHSC1L1-FGFR1 and EGFR VIII fusions were identified as the most common druggable fusions. All actionable fusion genes were found to interact with one or more of the following pathways RAS/RAF/MEK/ERK, PI3K/AKT/MTOR, PLCy/PKC and JAK/STAT. Although a targeted agent for TRK fusions now has FDA approval, this rearrangement appears to be a rare event. In contrast, inhibitors targeting the TBL1XR1-PIK3CA, MET-MET, WHSC1L1-FGFR1 fusions and linked downstream signalling pathways appear to offer much broader clinical utility. Conclusions: Druggable fusions were identified at an unexpectedly high frequency and should therefore be included as part of routine comprehensive precision oncology testing. Notably, many of the actionable fusions are not tumor type specific reinforcing the “site agnostic” approach to profiling and supporting the concept of “molecular basket” clinical trials. Precision oncology trending data also provides actionable mutational landscapes which can be used to refine precision oncology testing, patient selection for targeted therapy protocols and enhancement of clinical trial design.

The actionable genomic mutational landscape in solid tumours.

e13642 Background: The recent exponential increase in targeted agents and immunotherapies provide new therapeutic opportunities for patients with advanced cancers who have failed first line therapy. However, lack of comprehensive precision oncology testing as part of routine pathology assessment means potential therapeutic opportunities are difficult to identify or remain undiscovered for many patients. Methods: To address this unmet clinical need we established Oncofocus, a clinically validated, ISO15189/2012 and CLIA accredited, precision oncology test optimized for analysis of small diagnostic PWET clinical biopsy samples (sample acceptance 94%). Oncofocus detects actionable genetic variants in 505 genes linked to 764 anti-cancer targeted therapy protocols, either on-market FDA and EMA approved, carrying ESMO and NCCN guideline references or currently in clinical trials. Oncofocus trending data was analyzed for a real-life cohort of 1111 patients with the aim of determining the frequency of actionable mutations in this population. This cohort represent patients with advanced stage disease who underwent Oncofocus testing having failed first line treatment protocols. Results: Analysis of trending data revealed a complex mutational landscape in which 90% of solid tumors harbored actionable mutations. The majority of patients harbored one or more actionable mutations (median 2, range 0-13) affecting key cancer related regulatory networks including the PI3K/AKT/MTOR and RAS/RAF/MEK/MAPK signaling pathways, DNA-damage repair pathways and cell cycle checkpoints. Actionable genetic variants across 33 DNA Damage and Repair (DDR) genes were identified in 30% of tumors. Using a defined predictive cut point of &gt; 10% for tumor proportion score, PD-L1 expression levels were significantly raised in 19% of cases. Abrogation of DDR function and elevated PD-L1 levels were identified in 5% of patients, a subpopulation potentially more responsive to immunotherapy. Notably, many of the actionable mutations identified did not show linkage with histological type or site of origin. Conclusions: Our data indicates that comprehensive precision oncology testing should be strongly considered as part of the diagnostic work up for all patients with advanced cancers, independent of tumor type, thereby ensuring capture of all targeted therapy opportunities and accelerating “site agnostic” molecular basket clinical trials. Comprehensive precision oncology testing was performed successfully on routine biopsy samples circumventing the requirement for fresh tissue or large sample specimens.

New Approach to Enhance CO2 Capture of “Molecular Basket” Sorbent by Using 3-Aminopropyltriethoxysilane to Reshape Fumed Silica Support

Here we report a new approach to enhance CO2 capture and separation over solid molecular basket sorbent by re-organizing the aggregation of fumed silica (FS) support particles with the addition of ...

Abstract A34: Cancer immunotherapy clinical trials in K-MASTER project

Abstract The K-MASTER cancer precision medicine diagnosis and treatment enterprise (K-MASTER project) is a precision medicine cancer treatment clinical trial platform, which uses next-generation sequencing (NGS) panel to screen the actionable mutations in 10,000 patients with refractory solid tumors and assigns the patients to matched clinical trials. K-MASTER project was initiated in Korea in June 2017. From October 2017, we have analyzed NGS -based cancer panel to detect genomic variations in Korean cancer patients. Tumor DNA was analyzed by K-MASTER panel, which allows to detect variations of 375 genes. As of September 3, 2019, total 4,240 cancer patients were registered via KM-00 screening protocol. The mean depth of K-MASTER panel was 701x. The patient whose cancer has been confirmed of certain genomic variants can participate in matched clinical studies. As of September 2019, 11 clinical trials are successfully in process and another 6 are awaiting kickoff under the name of K-MASTER project. There are 3 ongoing immunotherapy clinical trials: avelumab for metastatic colon cancer with microsatellite instability-high or POLE mutation (KM-01), nivolumab for advanced solid tumor with DNA repair pathway aberration (KM-06), and spartalizumab combined with lacnotuzumab for esophageal squamous cell carcinoma (KM-12). Among them, the KM-01 study closed its registration and is waiting for data analysis. Other studies are actively enrolling patients along with KM-00 screening protocol. In addition, various new immunotherapy studies are preparing for initiation: basket trial of nivolumab plus ipilimumab for high tumor mutational burden solid tumors (KM-09), phase II study of CAST cell therapy (KM-15), alternative scheduling trial for pembrolizumab (KM-19), and phase II/III trial of novel PD-1 inhibitor INCMGA00012 (KM-20) are on their way to start. In conclusion, K-MASTER project is efficient to detect actionable variations and function as a reliable path between patient and new immunotherapeutic agent. Nationwide NGS-based screening is not only feasible but also effective in recruiting participants in molecular basket trials as well as immunotherapy trials. This novel knowledge provides an intriguing background to investigate new target approaches and to progress precision medicine. (This research was supported by a grant of the Korea Health Technology R&amp;D Project through the Korea Health Industry Development Institute [KHIDI], funded by the Ministry of Health &amp;Welfare, Republic of Korea [Grant number: HI17C2206].) Citation Format: Ju Won Kim, Jae Sook Sung, Hee Jun Jung, Jung Yoon Choi, Soo Hyeon Lee, Won Jin Chang, Yoon Ji Choi, Kyong Hwa Park, Yeul Hong Kim. Cancer immunotherapy clinical trials in K-MASTER project [abstract]. In: Proceedings of the AACR Special Conference on Tumor Immunology and Immunotherapy; 2019 Nov 17-20; Boston, MA. Philadelphia (PA): AACR; Cancer Immunol Res 2020;8(3 Suppl):Abstract nr A34.

Effect of support structure and polyamine type on CO2 capture in hierarchically structured monolithic sorbents

The objective of this work was to study properties of monolithic CO2 sorbents. The materials were obtained by molecular basket approach with polyethyleneimine (PEI) and grafting method using the silane-modified polyamines (trimethoxysilylpropyl-modified polyethylenimine and dimethoxymethylsilylpropyl-modified polyethylenimine). Adsorption measurements were carried out by means of thermogravimetry to determine the impact of the monolith structure, type of amine precursor and its loading on sorption capacity and performance of adsorption/desorption process. Highly effective sorbents were fabricated using hierarchically structured silica monoliths of cylindrical shape (dimension of 4 × 4 mm), which were characterized by large surface area, SBET, ca. 650 m2/g and high porosity (pore volume ca. 4.1 cm3/g). The PEI-modified sorbents, due to larger content of amine groups, enabled much more efficient CO2 capture in comparison to the grafted materials. The complexity of pore structure/amine loading/thickness of active layer/sorption capacity relationships was demonstrated. It was shown that the thickness of active layer had a strong impact on CO2 diffusion and accessibility of amine groups, and thus on the sorption performance. Due to large surface area of the hierarchically structured monolithic support, the thickness of active layer in sorbents highly loaded with polyamines was low and thus the accessibility to the adsorption centres was improved. Multiple adsorption/desorption cycles clearly demonstrated good stability and recyclability of PEI and silane-modified materials.

Comprehensive genomic analysis of metastatic pancreatic ductal adenocarcinoma (mPDAC) reveals a significant proportion of clinical actionable aberrations.

e15753 Background: Significant progress has been made in the understanding of the genomic landscape of PDAC, but the clinical utility of these data remains uncertain. Methods: As part of the BC Cancer Personalized Oncogenomics (POG) and PanGen studies (NCT02155621, NCT02869802), whole genome analysis and transcriptome sequencing were performed on fresh biopsy and blood sample from 48 mPDAC patients. Genomic findings informed therapy choices including potential eligibility for the CCTG PM.1 molecular basket trial (NCT03297606). Results: Cohort consists of 54.1% male, average age 57.6, 34/48 had ≥2 lines of treatment. 37/48 biopsies were from liver and 27/48 were collected pre-treatment. 8/48 (16.6%) patients had aberrations with strong evidence of clinical actionability. These include 2 germline BRCA2, 1 germline BRCA1, 1 somatic XRCC2 homozygous deletion with strong COSMIC signature 3, all predictive of platinum sensitivity. Patients with XRCC2 deletion and BRCA1 had over 2 years on FOLFIRINOX. Fusions affecting the NRG1 gene were identified in 3/4 patients with KRAS wildtype tumours, which may confer ERRB inhibitor sensitivity. 2/3 NRG1 fusion patients have thus far been treated with the ERBB inhibitor afatinib with radiographic responses noted in both patients. One patient had mismatch repair deficiency, and a high mutational burden, suggestive of immune checkpoint inhibitor sensitivity. Other possible actionable mutations include CCTG PM.1 trial potential eligibility: 4/48 with high homologous recombination defects and 1 germline ATM mutation loss (PARP inhibitor arm), 1/47 ERBB2 amplification (anti-HER2 arm), 2/47 high expression of FGFR1 (Sunitinib arm) and 1/47 with high FLT4 and IGF1R expression (Axitinib arm). Conclusions: More routine use of comprehensive genomic analysis should be considered in mPDAC given finding of high degree of actionability. Importantly, a significant proportion (16.6%) had findings with strong evidence of clinical impact.

Stereo- and Regioselective Synthesis of Molecular Baskets.

We describe a stereoselective method for obtaining multigram quantities of molecular basket 1 syn in overall 11% yield, using inexpensive cyclopentadiene and diethyl fumarate as starting materials. First, an asymmetric synthesis of enantioenriched bromo(trimethylstannyl)alkene (-)-8 was accomplished by the stereoselective bromination of dibromonorbornene (+)-4 guided by anchimeric assistance and subsequent syn- exo-elimination of tetrabromonorbornane (-)-5a as the key steps. Subsequent Cu(I)-catalyzed cyclotrimerization of (-)-8 was optimized to give 1 syn/ anti in 85% yield and 1:1 ratio of diastereomers. Importantly, the results of our mechanistic experiments were in line with the cyclotrimerization occurring in a chain-type fashion with racemization of a Cu(I) homochiral dimeric intermediate, reducing the stereoselectivity of the transformation. Enabled by more facile access to molecular baskets of type 1 syn, a range of recognition studies can now be completed for producing novel supramolecular catalysts, organophosphorus scavengers, and nanostructured materials.

Comprehensive genomic analysis of metastatic pancreatic ductal adenocarcinoma (mPDAC) reveals a significant proportion of clinical actionable aberrations.

273 Background: Substantial progress has been made in the understanding of the genomic landscape of PDAC, but the clinical utility of these data remains uncertain. Methods: As part of the BC Cancer Personalized Oncogenomics (POG) and PanGen studies, whole genome analysis and transcriptome sequencing were performed on fresh biopsy and blood sample from 47 mPDAC patients. Genomic findings informed therapy choices including potential eligibility for the CCTG PM.1 molecular basket trial. Results: Cohort consists of 53% male, average age 57.8, 34/47 had ≥2 lines of treatment. 37/47 biopsies were from liver and 26/47 were collected pre-treatment. 8/47 (17%) patients had aberrations with strong evidence of clinical actionability. These include 2 germline BRCA2, 1 germline BRCA1, 1 somatic XRCC2 homozygous deletion with strong COSMIC signature 3, all predictive of platinum sensitivity. Patients with XRCC2 deletion and BRCA1 had over 2 years on FOLFIRINOX. Fusions affecting the NRG1 gene were identified in 3 patients, all with KRAS wildtype tumours, which may confer ERRB inhibitor sensitivity. 1/3 NRG1 fusion patients had thus far been treated with the ERBB inhibitor afatinib, with reduction of CA19-9 from &gt;120,000 to 7246 and dramatic response noted on PET CT imaging one month post treatment. One patient had mismatch repair deficiency, and a high mutational burden, suggestive of immune checkpoint inhibitor sensitivity. In total 85% (40/47) sequenced mPDAC patients had potentially actionable mutations which includes CCTG PM.1 trial eligibility: 24/47 with cell cycle dysregulation (CDK4/6 inhibitor arm), 4/47 with high homologous recombination defects (PARP inhibitor arm), 1/47 ERBB2 amplification (anti-HER2 arm), 2/47 high expression of FGFR1 (Sunitinib arm) and 1/47 with high FLT4 and IGF1R expression (Axitinib arm). Conclusions: More routine use of comprehensive genomic analysis should be considered in mPDAC given finding of high degree of actionability. Importantly, a significant proportion (17%) had findings with strong evidence of clinical impact.(NCT02155621, NCT02869802, NCT03297606)

Cover Feature: Comparative Study of Molecular Basket Sorbents Consisting of Polyallylamine and Polyethylenimine Functionalized SBA‐15 for CO2 Capture from Flue Gas (ChemPhysChem 22/2017)

Cover Feature: Comparative Study of Molecular Basket Sorbents Consisting of Polyallylamine and Polyethylenimine Functionalized SBA‐15 for CO₂ Capture from Flue Gas (ChemPhysChem 22/2017)

Comparative Study of Molecular Basket Sorbents Consisting of Polyallylamine and Polyethylenimine Functionalized SBA-15 for CO2 Capture from Flue Gas.

Polyallylamine (PAA)-based molecular basket sorbents (MBS) have been studied for CO2 capture in comparison with polyethylenimine (PEI)-based MBS. The characterizations including N2 physisorption, diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS), and thermogravimetric analysis (TGA) showed that PAA (Mn =15 000) is more rigid and has more steric hindrance inside SBA-15 pores than PEI owing mainly to its different polymer structure. The effects of temperature and PAA loading on the CO2 sorption capacity of PAA-based MBS have been examined by TGA by using 100 % CO2 gas stream and compared with PEI/SBA-15. It was found that the capacity of the PAA/SBA-15 sorbent increased with increasing temperature. The optimum capacity of 88 mgCO2 gsorb-1 was obtained at 140 °C for PAA(50)/SBA-15 whereas the optimum sorption temperature was 75 and 90 °C for PEI-I(50)/SBA-15 (PEI-I, Mn =423) and PEI-II(50)/SBA-15 (PEI-II, Mn =25 000), respectively. The capacity initially increased with the increase of PAA loading and then dropped at high amine contents, owing to the increased diffusion barrier. The highest CO2 capacity of 109 mgCO2 gsorb-1 was obtained at a PAA loading of 65 wt %, whereas the PAA(50)/SBA-15 sorbent gave the best amine efficiency of 0.23 molCO2 molN-1 . The effect of moisture was examined in a fixed-bed flow system with simulated flue gas containing 15 % CO2 and 4.5 % O2 in N2 . It was found that the presence of moisture significantly enhanced CO2 sorption over PAA(50)/SBA-15 and greatly improved its cyclic stability and regenerability. Compared with PEI/SBA-15, PAA/SBA-15 possesses a better thermal stability and higher resistance to oxidative degradation. However, the CO2 sorption rate over the PAA(50)/SBA-15 sorbent was much slower.

CO2 capture over molecular basket sorbents: Effects of SiO2 supports and PEG additive

The objective of this work is to study the influences of silica supports and PEG additive on the sorption performance of molecular basket sorbent (MBS) for CO2 capture consisting of polyethylenimine and one of the following supports: SBA-15 (2-D structure), TUD-1 (3-D sponge-like structure) and fumed silica HS-5 (3-D disordered structure). Effects of the supports regarding pore structures and pore properties, the PEI loading amount as well as the sorption temperature were examined. Furthermore, polyethylene glycol (PEG) was introduced as an additive into the sorbents and its effect was investigated at different PEI loadings and sorption temperatures. The results suggest that the pore properties of MBS (after PEI loading) play a more important role in the CO2 sorption capacity, rather than those of the supports alone. MBS with 3D pore structure exhibits higher CO2 sorption capacity and amine efficiency than those with 2D-structured support. Among the sorbents studied, fumed silica (HS-5) based MBS showed the highest CO2 sorption capacity in the temperature range of 30–95 °C, probably due to its unique interstitial pores formed by the aggregation of polymer-loaded SiO2 particles. It was found that the temperature dependence is directly related to the PEI surface coverage layers. The more PEI surface coverage layers, the higher diffusion barrier for CO2 and the stronger temperature dependence of CO2 capacity. 3D MBS exceeds 2D MBS at the same PEI coverage layers due to lower diffusion barrier. Adding PEG can significantly enhance the CO2 sorption capacity and improve amine efficiency of all MBS, most likely by alleviating the diffusion barrier within PEI bulk layers through the inter-molecular interaction between PEI and PEG.

Selective Removal of H2S from Biogas Using Solid Amine-Based “Molecular Basket” Sorbent

Biogas is an important renewable energy source, but its ppm-level hydrogen sulfide (H2S) component must be removed from the gas mixture dominated by CO2 and CH4. In this work, a tertiary-amine-based “molecular basket” sorbent with a mesoporous silica as support was found to be effective for the selective hydrogen sulfide (H2S) removal from gas mixtures simulating biogas with a high CO2 concentration up to 40 vol %. Polyallylamine (PA), polyethylenimine (PEI), and tetramethyl hexanediamine (TMHDA) were used as primary, secondary, and tertiary amines to prepare the SBA-15 supported sorbents, respectively, and their H2S sorption performances were evaluated in a flow system in the absence and presence of CO2. The tertiary-amine-based sorbent, TMHDA/SBA-15, can selectively remove H2S in the presence of CO2, and the highest sorption capacity was achieved at 15 wt % TMHDA loading which is close to its monolayer coverage on the surface. More importantly, about 90% of the capacity could be maintained on TMHDA/SBA-...

Effect of amine structure on CO2 capture performance of amine-modified SBA-15

To investigate the relative CO2 capture performance of “molecular basket” type solid amine sorbents with varying amine structural characteristics, two model amine isomers, triethylenetetramine(TETA) and tris(2-aminoethyl)-amine(TAEA), were chosen alongside mesoporous silica SBA-15 as a support. The CO2 capture performance of each amine derivative was evaluated using a breakthrough method with a fixed-bed reactor. The results show that, in the absence of moisture, the SBA-TETA sorbents show better CO2 capture performance than the SBA-TAEA sorbents; on the other hand, in the presence of moisture, the SBA-TAEA sorbents show slightly improved uptake compared to the SBA-TETA sorbents. The tertiary amine groups, such as those found on TAEA, are known to be un-reactive with CO2 in the absence of moisture, but is activated in the presence of moisture may account for these findings.

Polynuclear Li12F13 − anion as a steric shielding agent with respect to selected metal ions

Polynuclear superhalogen anion Li12F13 − and its ionic complexes formed by the interaction with selected metal ions (i.e., Li12F13 −Na+, Li12F13 −K+, Li12F13 −Mg2+, and Li12F13 −Zn2+) are proposed and investigated on the basis of ab initio calculations. The thermodynamic stability, vertical excess electron detachment energy, and binding energies between ionic components were examined and discussed. The Li12F13 − anion has been proved stable against fragmentation and its vertical electronic stability was found to approach 10 eV. Due to its specific equilibrium structure that resembles a molecular basket, the Li12F13 − anion was found capable of trapping positively charged metal ions inside to form strongly bound ionic complexes. The large values of binding energies predicted for the Li12F13 −Na+, Li12F13 −K+, Li12F13 −Mg2+, and Li12F13 −Zn2+ systems and their specific equilibrium structures indicate that the Li12F13 − anion can be useful as a steric shielding system which protect the metal ions from the interaction with the surroundings.