scholarly journals Growth Study of Hierarchical Pore SSZ-13 Molecular Sieves with Improved CO2 Adsorption Performance

Nanomaterials ◽  
2021 ◽  
Vol 11 (12) ◽  
pp. 3171
Author(s):  
Runlin Han ◽  
Yuxuan Tao ◽  
Liang Zhou
Keyword(s):  
Pore Structure ◽  
Molecular Sieves ◽  
Molecular Sieve ◽  
Co2 Adsorption ◽  
Fluoride Ions ◽  
Structure Directing Agent ◽  
Small Unit ◽  
Excellent Thermal Stability ◽  
Adsorption Performance ◽  
Hierarchical Pore

SSZ-13, with a unique pore structure and excellent thermal stability, showed a potential application in the adsorption and catalysis industry. In this work, Al(NO3)3 was used as an Al source to study the performance and morphology of the zeolite. The zeolite was prepared with an unconventional process by adding an Al source before the structure-directing agent and base. When inorganic oxygen-containing anions were introduced into the unconventional synthesis system, the crystals of the zeolite conform to the unconventional growth mode. The zeolites with large crystals were assembled from small unit nanocrystals. Extending the reaction time, aging time and adding fluoride ions introduced a multistage pore structure on the surface of the molecular sieve, which improved the CO2 adsorption performance. When aging for 24 h, reaction for 96 h, and the amount of fluorine added was 0.05 (F/Si), the sample had the best hierarchical pore structure. The SSZ-13 molecular sieve with an added amount of 0.1 (F/Si) has the highest CO2 adsorption performance. The adsorption amount was 4.55 mmol/g at 1 bar, which is 20.4% higher than that of zeolite SSZ-13 prepared by the conventional process.

scholarly journals Optimized Preparation of Nanosized Hollow SSZ-13 Molecular Sieves with Ultrasonic Assistance

Nanomaterials ◽  
2020 ◽  
Vol 10 (11) ◽  
pp. 2298
Author(s):  
Liang Zhou ◽  
Runlin Han ◽  
Yuxuan Tao ◽  
Jinqu Wang ◽  
Yiwei Luo
Keyword(s):  
Adsorption Capacity ◽  
Molecular Sieves ◽  
Molecular Sieve ◽  
Co2 Adsorption ◽  
Hollow Structure ◽  
Preparation Time ◽  
Cubic Crystal ◽  
Adsorption Performance ◽  
Ultrasonic Time ◽  
Co2 Adsorption Capacity

Because of its unique eight-membered ring pore structure and the arrangement of cations in its structure, the SSZ-13 molecular sieve has a higher affinity for CO2 than other gases, meaning it has attracted more attention than other porous materials for CO2 adsorption. However, the expensive template and long preparation time limits the industrial production of SSZ-13. In this work, a hollow structure was successfully introduced into the nanosized SSZ-13 molecular sieve with ultrasonic treatment. The effects of the amount of seed added and the ultrasonic time on the structure were investigated. When the amount of seed added was 0.5 wt.% and the ultrasonic time was 60 min, the sample showed a hollow cubic crystal with a diameter of about 50 nm. The specific surface area reached 791.50 m2/g, and the mesoporous ratio was 66.3%. The samples were tested for CO2 adsorption performance at 298 K. It was found that the hollow sample prepared in this work has higher CO2 adsorption capacity compared with the SSZ-13 zeolite prepared with conventional methods. When the adsorption pressure was 0.27 bar, the adsorption amount reached 2.53 mmol/g. The hollow SSZ-13 molecular sieve reached a CO2 adsorption capacity of 4.24 mmol/g at 1 bar.

scholarly journals Effect of Ammonia Activation and Chemical Vapor Deposition on the Physicochemical Structure of Activated Carbons for CO2 Adsorption

Processes ◽  
2019 ◽  
Vol 7 (11) ◽  
pp. 801
Author(s):  
Liu ◽  
Li ◽  
Dong ◽  
Li ◽  
Feng ◽  
...  
Keyword(s):  
Chemical Vapor Deposition ◽  
Pore Structure ◽  
Nitrogen Content ◽  
Vapor Deposition ◽  
Co2 Adsorption ◽  
Activated Carbons ◽  
Chemical Vapor ◽  
Physical Activation ◽  
Adsorption Performance ◽  
Physicochemical Structure

Focusing on the bottlenecks of traditional physical activation method for the preparation of activated carbons (ACs), we established a simple and scalable method to control the physicochemical structure of ACs and study their CO2 adsorption performance. The preparation is achieved by ammonia activation at different volume fractions of ammonia in the mixture (10%, 25%, 50%, 75%, and 100%) to introduce the nitrogen-containing functional groups and form the original pores and subsequent chemical vapor deposition (CVD) at different deposition times (30, 60, 90, and 120 min) to further adjust the pore structure. The nitrogen content of ACs-0.1/0.25/0.5/0.75/1 increases gradually from 2.11% to 8.84% with the increase of ammonia ratio in the mixture from 10% to 75% and then decreases to 3.02% in the process of pure ammonia activation (100%), during which the relative content of pyridinium nitrogen (N-6), pyrrolidine (N-5), and graphite nitrogen (N-Q) increase sequentially but nitrogen oxygen structure (N-O) increase continuously. In addition, ACs-0.5 and ACs-0.75, with a relatively high nitrogen content (6.37% and 8.84%) and SBET value (1048.65 m2/g and 814.36 m2/g), are selected as typical samples for subsequent CVD. In the stage of CVD, ACs-0.5-60 and ACs-0.75-90, with high SBET (1897.25 and 1971.57 m2/g) value and an appropriate pore-size distribution between 0.5 and 0.8 nm, can be obtained with the extension of deposition time from 60 to 90 min. The results of CO2 adsorption test indicate that an adsorption capacity of ACs-0.75-90, at 800 mmHg, is the largest (6.87 mmol/g) out of all the tested samples. In addition, the comparison of CO2 adsorption performance of tested samples with different nitrogen content and pore structure indicates that the effect of nitrogen content seems to be more pronounced in this work.

Improvement of Adsorption Performance Based on Metal Ion Modified ETS-4 Molecular Sieves

2013 ◽  
Vol 815 ◽  
pp. 437-442 ◽  
Author(s):  
Li Yun Song ◽  
Xiao Jun Liu ◽  
Zong Cheng Zhan ◽  
Hong He ◽  
Xue Hong Zi ◽  
...  
Keyword(s):  
Molecular Sieves ◽  
Molecular Sieve ◽  
Metal Ion ◽  
Room Temperature ◽  
Raw Materials ◽  
Ni Doping ◽  
Adsorption Performance ◽  
Adsorption Capacities ◽  
Titanium Trichloride ◽  
Significant Change

Titanosilicate ETS-4 with the Sr and Ni cations modification were prepared by hydrotherrmal method using titanium trichloride and tetraethoxysilane as raw materials. The properties and morphology of the materials were characterized by XRD, SEM techniques, Sr and Ni introduced to the molecular sieve affected the frame contraction when they were heated, and did little effect on the crystallization and morphology. N2and CH4isotherms of each sample were measured at room temperature. The Sr and Ni doping could improve the N2and CH4adsorption capacities of ETS-4. The capacities of the two gases increased in the pressurization process for ETS-4-Sr and ETS-4-Ni, with the pressure increasing, no significant change in capacities of N2and CH4was observed over the ETS-4 sample. Compared to ETS-4 molecular sieves, the capacity for N2of ETS-4-Sr and ETS-4-Ni at the pressure of 1200 mmHg increased 4.2 and 3.9 times, respectively. At last, the results indicated that the cations doping (Sr2+and Ni2+) can improve the adsorption performance of ETS-4 greatly.

scholarly journals Pore Structure Alteration of a Carbon Molecular Sieve for the Separation of Hydrogen Sulfide from Methane by Adsorption

1993 ◽  
Vol 10 (1-4) ◽  
pp. 193-201 ◽  
Author(s):  
Z.J. Pan ◽  
S.G. Chen ◽  
J. Tang ◽  
R.T. Yang
Keyword(s):  
Natural Gas ◽  
Pore Structure ◽  
Molecular Sieves ◽  
Molecular Sieve ◽  
Carbon Deposition ◽  
Important Variable ◽  
Equilibrium Adsorption ◽  
Carbon Molecular Sieve ◽  
Natural Gas Desulfurization ◽  
Kinetic Selectivity

The equilibrium adsorption of H2S is substantially stronger than that of CH4 on carbons, including carbon molecular sieve (CMS). A carbon molecular sieve with a proper pore structure can provide a kinetic selectivity for H2S over CH4, thus further enhancing the overall selectivity (equilibrium plus kinetic) for H2S and providing the basis of natural gas desulfurization by adsorption. Kinetic selectivity requires a unique pore structure due to the small difference in the molecular dimensions of H2S and CH4 (~0.2 Å). Equilibrium and diffusion rate data for CH4 and H2S at 25°C have been measured in three commercial carbon molecular sieves: Bergbau Forschung CMS, Takeda CMS 3A and Takeda CMS 5A. The pores are either too small (in the two former carbons) or too large (in CMS 5A) for H2S/CH4 separation. Alterations to the pore structure either by controlled oxidation or carbon deposition by pyrolysis have been studied. Optimal results were obtained by pyrolysis of propylene on CMS 5A under the following conditions: 0.05 atm, 700°C, 5 min, weight gain of 0.67%. The resulting carbon molecular sieve retained the high equilibrium adsorption capacities while yielding a diffusion time constant ratio for H2S/CH4 of 8.2. This carbon is suitable for natural gas desulfurization by adsorption processes such as pressure swing adsorption. Temperature was the most important variable in pore structure alteration by carbon deposition. Under the optimal pyrolysis conditions, carbon was only deposited near the pore entrances.

Hierarchical pore structure of zeolite/MCM obtained by supramolecular templating using ionic liquid (C16MI·Cl) as the structure-directing agent

2019 ◽  
Vol 55 (6) ◽  
pp. 2343-2352
Author(s):  
Victor de Aguiar Pedott ◽  
Iemedelais Bordin ◽  
Alan dos Santos da Silva ◽  
Diego Ivan Petkowicz ◽  
Diana Exenberger Finkler ◽  
...  
Keyword(s):  
Ionic Liquid ◽  
Pore Structure ◽  
Structure Directing Agent ◽  
Hierarchical Pore Structure ◽  
Hierarchical Pore

Crystallization of the Granulated Molecular Sieve SAPO-11 Having High Crystallinity and a Hierarchical Pore Structure

2020 ◽  
Vol 20 (3) ◽  
pp. 167-173
Author(s):  
M. R. Agliullin ◽  
Z. R. Khairullina ◽  
B. I. Kutepov
Keyword(s):  
Specific Surface ◽  
Pore Structure ◽  
Molecular Sieve ◽  
Joint System ◽  
Phase Purity ◽  
High Crystallinity ◽  
Hierarchical Pore Structure ◽  
Crystallization Method ◽  
Hierarchical Pore ◽  
First Time

A method for the synthesis of the granulated molecular sieve SAPO-11 having high crystallinity and a hierarchical pore structure was proposed for the first time. Crystallization is based on the synthesis of granules comprising 70 wt.% of powdered SAPO-11 and 30 wt.% of the silicoaluminophosphate binder, which transforms into SAPO-11 during crystallization and forms a joint system of intergrown silicoaluminophosphate crystals. This crystallization method makes it possible to obtain the granulated SAPO-11 having high crystallinity and phase purity; its specific surface area SBET is 212 m2/g, micro, meso- and macropore volumes are 0.08, 0.11 and 0.55 cm3/g, respectively. Meso- and macropores were shown to form between intergrown SAPO-11 crystals.

scholarly journals Study on the Compatibility of Gas Adsorbents Used in a New Insulating Gas Mixture C4F7N/CO2

Processes ◽  
2019 ◽  
Vol 7 (10) ◽  
pp. 698 ◽  
Author(s):  
Huang ◽  
Wang ◽  
Liu ◽  
Zhang ◽  
Zeng
Keyword(s):  
Adsorption Capacity ◽  
Molecular Sieves ◽  
Co2 Adsorption ◽  
High Adsorption ◽  
Environment Friendly ◽  
Adsorption Performance ◽  
Co2 Adsorption Capacity ◽  
Liquefaction Temperature ◽  
Electricity Transfer

An environment-friendly insulating gas, perfluoroisobutyronitrile (C4F7N), has been developed recent years. Due to its relatively high liquefaction temperature (around −4.7 °C), buffer gases, such as CO2 and N2, are usually mixed with C4F7N to increase the pressure of the filled insulating medium. During these processes, the insulating gases may be contaminated with micro-water, and the mixture of H2O with C4F7N could produce HF under breakdown voltage condition, which is harmful to the gas insulated electricity transfer equipment. Therefore, removal of H2O and HF in situ from the gas insulated electricity transfer equipment is significant to its operation security. The adsorbents with the ability to remove H2O but without obvious C4F7N/CO2 adsorption capacity are essential to be used in this system. In this work, a series of industrial adsorbents and desiccants were tested for their compatibility with C4F7N/CO2. Pulse adsorption tests were conducted to evaluate the adsorption performance of these adsorbents and desiccants on C4F7N and CO2. The 5A molecular sieve showed high adsorption of C4F7N (22.82 mL/g) and CO2 (43.86 mL/g); F-03 did not show adsorption capacity with C4F7N, however, it adsorbed CO2 (26.2 mL/g) clearly. Some other HF adsorbents, including NaF, CaF2, MgF2, Al(OH)3, and some desiccants including CaCl2, Na2SO4, MgSO4 were tested for their compatibility with C4F7N and CO2, and they showed negligible adsorption capacity on C4F7N and CO2. The results suggested that these adsorbents used in the gas insulated electricity transfer equipment filled with SF6 (mainly 5A and F-03 molecular sieves) are not suitable anymore. The results of this work suggest that it is a good strategy to use a mixture of desiccants and HF adsorbents as new adsorbents in the equipment filled with C4F7N/CO2.

Template-free amine-bridged silsesquioxane with dangling amino groups and its CO2 adsorption performance

2018 ◽  
Vol 6 (46) ◽  
pp. 23690-23702 ◽  
Author(s):  
Dang Viet Quang ◽  
Abdallah Dindi ◽  
Khalid Al-Ali ◽  
Mohammad R. M. Abu-Zahra
Keyword(s):  
Co2 Adsorption ◽  
Condensation Process ◽  
Amino Groups ◽  
Structure Directing Agent ◽  
Adsorption Performance ◽  
Free Amine ◽  
Bridged Silsesquioxane ◽  
Hydrolysis And Condensation ◽  
Template Free

Amine-bridged silsesquioxane with dangling amino groups was prepared by a hydrolysis and condensation process without using any template or structure-directing agent.

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