Capturing CO2 Emissions in the George C. Wallace Tunnel: A Case Study

This paper describes the design of a ventilation system to be paired with a carbon capture system. The ventilation system utilizes the geometry of the George C. Wallace tunnel, located in the City of Mobile, Alabama, USA to capture and redirect emissions to a direct air capture (DAC) device to sequester 25% of the total CO2 mass generated from inside the tunnel. The total CO2 mass rate for the westbound traffic between the week-day hours of 7 a.m. and 6 p.m. has been estimated between 2,300 to 3,000 lbs./hr. By sequestering these emissions, the overall surrounding air quality was shown to be improved to a level that mirrors that from the pre-US industrial era of 270 ppm.

New process development and process evaluation for capturing CO2 in flue gas from power plants using ionic liquid[emim][Tf2N]

Using the ionic liquid[emim][Tf2N]as a physical solvent,it was found by Aspen Plus simulation that it was possible to attempt to capture CO2 from the flue gas discharged from the coal-fired unit of the power plant.Using the combination of model calculation and experimental determination,the density,isostatic heat capacity,viscosity,vapor pressure,thermal conductivity,surface tension and solubility of[emim][Tf2N]were obtained.Based on the NRTL model,the Henry coefficient and NRTL binary interaction parameters of CO2 dissolved in[emim][Tf2N]were obtained by correlating[emim][Tf2N]with the gas–liquid equilibrium data of CO2.Firstly,the calculated relevant data is imported into Aspen Plus,and the whole process model of the ionic liquid absorption process is established.Then the absorption process is optimized according to the temperature distribution in the absorption tower to obtain a new absorption process.Finally,the density,constant pressure heat capacity,surface tension,thermal conductivity,and viscosity of[emim][Tf2N]were changed to investigate the effect of ionic liquid properties on process energy consumption,solvent circulation and heat exchanger design.The results showed that based on the composition of the inlet gas stream to the absorbers,CO2 with a capture rate of 90%and a mass purity higher than 99.5%was captured.These results indicate that the[emim][Tf2N]could be used as a physical solvent for CO2 capture from coal-fired units.In addition,the results will provide a theoretical basis for the design of new ionic liquids for CO2 capture.

Synthesis of Liquid-like Trisilanol Isobutyl-POSS NOHM and Its Application in Capturing CO2

The trisilanol isobutyl polyhedral oligomeric silsesquioxane（POSS） was fabricated into liquid-like nano- particle organic hybrid materials（NOHMs） with ）,-（2,3-epoxypropoxy）propytrimethoxysilane as corona and polyethe- ramine M2070 as canopy, and the product was called liquid-like POSS NOHM. The liquid-like POSS NOHM has a low viscosity at room temperature without any solvent and the mass fraction of trisilanol isobutyl POSS was 23.38%. The liquid-like POSS NOHM shows great CO2 capturing property with a capacity of 2.108 mmol/g（PCO2=6 MPa）. The physical adsorption increased obviously with the pressure going up and it may make a difference between liquid-like POSS NOHMs and traditional monoethamolamine（MEA） based CO2 absorbent. The recycle property was also studied. The NOHM behaved as fresh product even after 10 cycles.

Clathrate Hydrate Capture of CO2 from Simulated Flue Gas with Cyclopentane/Water Emulsion

Capture of CO2 by hydrate is one of the attractive technologies for reducing greenhouse effect.The primary challenges are the large energy consumption,low hydrate formation rate and separation efficiency.This work presents a new method for capture of CO2 from simulated flue gasCO2(16.60%,by mole) /N2 binary mixture by formation of cyclopentane(CP) hydrates at initial temperature of 8.1°C with the feed pressures from 2.49 to 3.95 MPa.The effect of cyclopentane and cyclopentane/water emulsion on the hydrate formation rate and CO2 separation efficiency was studied in a 1000 ml stirred reactor.The results showed the hydrate formation rate could be increased remarkably with cyclopentane/water emulsion.CO2 could be enriched to 43.97%(by mole) and 35.29%(by mole) from simulated flue gas with cyclopentane and cyclopentane/water(O/W) emulsion,respectively,by one stage hydrate separation under low feed pressure.CO2 separation factor with cyclopentane was 6.18,higher than that with cyclopentane/water emulsion(4.01) ,in the range of the feed pressure.The results demonstrated that cyclopentane/water emulsion is a good additive for efficient hydrate capture of CO2.

Impact of organic interlayer anions on the CO2 adsorption performance of Mg-Al layered double hydroxides derived mixed oxides

Herein we report a systematical investigation on the promoting effect of the carbon chain length of the intercalated carboxylic anions on the COcapture performance of Mg-Al layer double hydroxides（LDHs）.A series of organo-LDHs were successfully synthesized via co-precipitation and calcination-rehydration methods. All as-prepared samples were characterized by many techniques including XRD, ATR-FTIR, BET,and TGA. The XRD and ATR-FTIR studies indicated that organic anions were successfully intercalated into LDHs. The influence of some important parameters such as calcination temperature, adsorption temperature, and coating with（Li-Na-K）NOmolten salt was investigated. The results exhibited that when the number of carbon is greater than 10, the COcapture capacity steadily increased with the increase in carbon number. After coating with 55 mol%（Li-Na-K）NOmolten salt, the COuptake of LDH-C16 sample with high Mg/Al ratios can be increased up to 3.25 mmol/g. The COadsorption/desorption cycling stability was also studied using temperature swing adsorption, which showed a stable COcapture performance even after 22 cycles. Considering its high COcapture capacity and good cycling stability, this novel COadsorbent is very promising in the sorption-enhanced water gas shift（SEWGS） processes.

A comparative study of MEA and DEA for post-combustion CO2 capture with different process configurations

This paper presented a comparative study of monoethanolamine （MEA） and diethanolamine （DEA） for post- combustion CO2 capture （PCC） process with different process configurations to study the interaction effect between solvent and process. The steady state process model of the conventional MEA-based PCC process was developed in Pro/II and was validated with the experimental data. Then ten different process configurations were simulated for both MEA and DEA. Their performances in energy consumption were compared in terms of reboiler duty and total equivalent work. The results show that DEA generally has better thermal performances than MEA for all these ten process configurations. Seven process configurations provide 0.38%-4.61% total energy saving compared with the conventional PCC process for MEA, and other two configurations are not favourable. For DEA, except one configuration, other process configurations have 0.27%-4.50% total energy saving. This work also analyzed the sensitivities of three key parameters （amine concentration, stripper pressure and lean solvent loading） in conventional process and five process modifications to show optimization strategy.

Improvement of CO2 capture performance of calcium-based absorbent modified with palygorskite

Limestone can be used for CO_2 capture and sequestration(CCS) in flue gas effectively. However, its CCS capability will dramatically decline after several cycles due to the surface "sintering". In this work, the limestone was modified with palygorskite to reduce sintering phenomenon between the absorbent particles during the CCS process and the carbonation rate of the limestone can be enhanced effectively. Palygorskite is a natural mineral with nano-fibrous structure which can reduce the mutual contact of limestone particles during the CCS process. The results were detected by TGA, SEM, MIP, FTIR and particle size analyzer respectively. The best CO_2 capture performance of modified absorbent was 13.11% improvement with only 5 wt% palygorskite added during the CCS process after 15 cycles compared with natural absorbent. It was found that excellent microscopic structures of absorbent modified with palygorskite was created, and the surface sintering was postponed leading to CO_2 capture performance enhanced under the same conditions.

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 COcapture 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 COsorption capacity, rather than those of the supports alone.MBS with 3D pore structure exhibits higher COsorption capacity and amine efficiency than those with 2D-structured support. Among the sorbents studied, fumed silica（HS-5） based MBS showed the highest COsorption capacity in the temperature range of 30-95 °C, probably due to its unique interstitial pores formed by the aggregation of polymer-loaded SiOparticles. 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 COand the stronger temperature dependence of COcapacity. 3D MBS exceeds 2D MBS at the same PEI coverage layers due to lower diffusion barrier. Adding PEG can significantly enhance the COsorption 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.

Economic Comparison of Three Gas Separation Technologies for CO2 Capture from Power Plant Flue Gas

Three gas separation technologies,chemical absorption,membrane separation and pressure swing adsorption,are usually applied for CO2 capture from flue gas in coal-fired power plants.In this work,the costs of the three technologies are analyzed and compared.The cost for chemical absorption is mainly from $30 to $60 per ton(based on CO2 avoided),while the minimum value is $10 per ton(based on CO2 avoided).As for membrane separation and pressure swing adsorption,the costs are $50 to $78 and $40 to $63 per ton(based on CO2 avoided),respectively.Measures are proposed to reduce the cost of the three technologies.For CO2 capture and storage process,the CO2 recovery and purity should be greater than 90%.Based on the cost,recovery,and purity,it seems that chemical absorption is currently the most cost-effective technology for CO2 capture from flue gas from power plants.However,membrane gas separation is the most promising alternative approach in the future,provided that membrane performance is further improved.

Facile synthesis of microporous carbonaceous materials derived from a covalent triazine polymer for CO2 capture

Highly porous nitrogen-doped carbon materials were synthesized by the carbonization of a low-cost porous covalent triazine polymer, PCTP-3, which had been synthesized by the AlClcatalyzed FriedelCrafts reaction of readily available monomers. The nature of the bond and structure of the resulting materials were confirmed using various spectroscopic methods, and the effects of KOH activation on the textural properties of the porous carbon materials were also examined. The KOH-activated porous carbon（aPCTP-3c） materials possessed a high surface area of 2271 mgand large micro/total pore volumes of 0.87/0.95 cmg, respectively, with narrower micropore size distributions than the porous carbon prepared without activation（PCTP-3c）. The aPCTP-3c exhibited the best COuptakes of 284.5 and 162.3 mg gand CHuptakes of 39.6 and 25.9 mg gat 273 and 298 K/1 bar, respectively, which are comparable to the performance of some benchmark carbon materials under the same conditions. The prepared materials exhibited high CO/Nselectivity and could be regenerated easily.

Synthesis and evaluation of carbon nanotubes composite adsorbent for CO2 capture： a comparative study of CO2 adsorption capacity of single-walled and multi-walled carbon nanotubes

As a preliminary investigation towards obtaining carbon nanotube composite adsorbent for CO2 capture, in this study CO2 adsorption performance of three commercial carbon nanotubes （CNTs） one single-walled carbon nanotubes （SWCNTs）, and two （2） different multi-walled carbon nanotubes （referred to as A-MWCNTs and B-MWCNTs） were evaluated and compared. The purpose of this study was to compare the different types of CNTs and select the best to serve as the solid anchor in the development of a hydrophobic composite adsorbent material for CO2 capture. The N2 physi- sorption of the CNTs was conducted to determine their surface area, pore volume and pore size. In addition, morphology and purity of the CNTs were checked with Transmission Electron Microscopy and Raman Spectroscopy, respectively. The CO2 adsorption capacity of the CNTs was evaluated using Thermo-gravimetric analysis （TGA） at 1.1 bar, at operating temperature ranged from 25 to 55 ~C and at different CO2 feed flow rates, in order to evaluate the effects of these variables on the CO2 adsorption capacity. The results of CO2 adsorption with the TGA show that CO2 adsorption capacity for both SWCNTs and MWCNTs was the highest at 25 ~C. Changing the CO2 flowrates had no significant effect on the adsorption capacity of MWCNTs, but decreasing the CO2 flow rate resulted in the enhancement of the CO2 adsorption capacity of SWCNTs. Overall, it was found that the SWCNTs displayed the highest CO2 adsorption capacity （29.97 gCO2/kg ad- sorbent） when compared to the MWCNTs （12.09 gCO2/kg adsorbent）, indicating a 150% increase in adsorption capacity over MWCNTs.

Experimental Study on Enhancement of Bubble Absorption of Gaseous CO2 with Nanofluids in Ammonia

In order to study the effects of nanoparticles on the CO_2 absorption in ammonia,nanofluids with different ammonia concentration and different nanoparticle solid loading were prepared by a two-step method.The nanofluids-enhanced gas absorption test devices were also established. The CO_2 absorption in TiO_2,CuO,SiO_2 nanofluids,which nanoparticles solid loading were 1. 0-8. 0 g/L,was tested respectively. In comparison with the blank absorption experiment,the effects of nanoparticle solid loading,nanoparticle types,ammonia concentration on the removal efficiency and removal rate were obtained. Experimental results show that adding nanoparticles can enhance the removal efficiency and removal rate,which increase first and then decrease with the increase of nanoparticle solid loading,and there exists an optimum solid loading of TiO_2 nanoparticles. The effect of SiO_2 nanofluid is inhibitory on the reaction. The enhancement factor of CuO nanofluid is always hovering around 1,which does not show the obvious enhancement or inhibition on the reaction. The optimum solid loading decreases gradually with the increase of ammonia concentration. In addition,according to the experimental results,the mechanism of enhanced absorption was analyzed theoretically.

Post-synthesis modification of porous organic polymers with amine： a task-specific microenvironment for CO2 capture

A porous organic polymer named FC-POP was facilely synthesized with extraordinary porosity and excellent stability. Further covalent incorporation of various amines including single amine group, multi-amine groups of diethylenediamine （DETA）, and poly-amine groups of polyethylenimine （PEI） to the network gave rise to task-specific modification of the microenvironments to make them more suitable for CO2 capture. As a result, significant boost of CO2 adsorption capacity of 4.5 mmol/g （for FC-POP-CH2DETA, 273 K, 1 bar） and the CO2/N2 selectivity of 736.1 （for FC- POP-CH2PEI） were observed after the post-synthesis amine modifications. Furthermore, these materials can be regener- ated in elevated temperature under vacuum without apparent loss of CO2 adsorption capacity.

Coassembled ionic liquid/laponite hybrids as effective CO2 adsorbents

Hybrid adsorbents for COcapture were prepared by coassembling laponite（LP） nanosheets and 1-nbutyl-3-methylimidazolium chloride（BMIMCl）. The prepared BMIMCl/LP layered hybrids were systematically characterized. The interlayer distance of the BMIMCl/LP layered hybrids expanded with an increasing concentration of BMIMCl, indicating that cumulative BMIMCl was intercalated into the LP layers. The efficiency of BMIMCl toward COcapture was significantly enhanced after it was immobilized within LP layers.

Modeling the rate of corrosion of carbon steel using activated diethanolamine solutions for CO2 absorption

A mechanistic model is developed to investigate the influence of an activator on the corrosion rate of carbon steel in the absorption processes of carbon dioxide(CO2).Piperazine(PZ)is used as the activator in diethanolamine(DEA)aqueous solutions.The developed model for corrosion takes into consideration the effect of fluid flow,transfer of charge and diffusion of oxidizing agents and operating parameters like temperature,activator concentration,CO2 loading and pH.The study consists of two major models:Vapor–liquid Equilibrium(VLE)model and electrochemical corrosion model.The electrolyte-NRTL equilibrium model was used for determination of concentration of chemical species in the bulk solution.The results of speciation were subsequently used for producing polarization curves and predicting the rate of corrosion occurring at the surface of metal.An increase in concentration of activator,increases the rate of corrosion of carbon steel in mixtures of activated DEA.

A comparative process simulation study of Ca-Cu looping involving post-combustion CO2 capture

This work presents a simulation study of several Ca-Cu looping variants with CO(2)capture,aiming at both parameter optimization and exergy analysis of these Ca-Cu looping systems.Three kinds of Ca-Cu looping are considered:(1)carbonation-calcination/reduction-oxidation;(2)carbonation-oxidation-calcination/reduction and (3)carbona tion/oxidation-calcination/reduction.A conventional Ca looping is also simulated for comparison.The influences of the calcination temperature on the mole fractions of CO(2)and CaO at the calciner outlet,the CaCO3 flow rate on the carbonator performance and the Cu/Ca ratio on the calciner performance are analyzed.The second kind of Ca-Cu looping has the highest carbonation conversion.At 1×10^5 Pa and 820℃,complete decomposition of CaCO3 can be achieved in three Ca-Cu looping systems,while the operation condition of 1×10^5 Pa,840℃is required for the conventional Ca looping system.Furthermore,the Cu/Ca molar ratio of 5.13-5.19 is required for the Ca-Cu looping.Exergy analyses show that the maximum exergy destruction occurs in the calciner for the four modes and the second Ca-Cu looping system(i.e.,carbonation-oxidation-calcination/reduction)performs the highest exergy efficiency,up to 65.04%,which is about 30%higher than that of the conventional Ca looping.

A robust predictive tool for estimating CO2 solubility in potassium based amino acid salt solutions

The acid gas absorption in four potassium based amino acid salt solutions was predicted using artificial neural network(ANN). Two hundred fifty-five experimental data points for CO_2 absorption in the four potassium based amino acid salt solutions containing potassium lysinate, potassium prolinate, potassium glycinate, and potassium taurate were used in this modeling. Amine salt solution's type, temperature, equilibrium partial pressure of acid gas, the molar concentration of the solution, molecular weight, and the boiling point were considered as inputs to ANN to prognosticate the capacity of amino acid salt solution to absorb acid gas. Regression analysis was employed to assess the performance of the network. Levenberg–Marquardt back-propagation algorithm was used to train the optimal ANN with 5:12:1 architecture. The model findings indicated that the proposed ANN has the capability to predict precisely the absorption of acid gases in various amino acid salt solutions with Mean Square Error(MSE) value of 0.0011, the Average Absolute Relative Deviation(AARD) percent of 5.54%,and the correlation coefficient(R^2) of 0.9828.

Application of Amine-Functionalized Cellulose Foam for CO2 Capture and Storage in the Brewing Industry

Due to a lack of technology,smaller breweries simply dump excess CO2 into the atmosphere,fueling the greenhouse effect and global warming.State-of-the-art CO2 capture technologies using nanofibrillated cellulose are expensive and require laborious freeze-drying.Consequently,there is a high demand for affordable alternatives in order to reduce the environmental impact in this industry sector.This work describes a novel route for a quick and cost-efficient synthesis of amine-functionalized cellulose pellets by a surfactantassisted steam explosion process.Typical values with this method were porosity of 92%and density of 67 g/cm^3.Investigations on polyethylenimine(PEI)content and distribution revealed a maximum PEI concentration of 20 wt%with decreasing concentration to the core of a pellet.Sufficient stability against brewery exhaust gas was determined and CO2 release at^120℃ could be confirmed.Capacity tests under simulated working conditions with a novel laboratory reactor yielded a CO2 capacity of 1.0 mmol/g or 67 mol/m^3,which is comparable to values known from the literature for other cellulose-based adsorbents.

Development of CO2 Selective Poly（Ethylene Oxide）-Based Membranes： From Laboratory to Pilot Plant Scale

Membrane gas separation is one of the most promising technologies for the separation of carbon dioxide （CO2） from various gas streams. One application of this technology is the treatment of flue gases from combustion processes for the purpose of carbon capture and storage. For this application, poly（ethylene oxide）-containing block copolymers such as Pebax or PolyActiveTM polymer are well suited. The thin-film composite membrane that is considered in this overview employs PolyActiveTM polymer as a selective layer material. The membrane shows excellent CO2 permeances of up to 4 m^3（STP）.（m^2·h·bar）^-1 （1 bar = 105 Pa） at a carbon dioxide/nitrogen （CO2/N2） selectivity exceeding 55 at ambient temperature. The membrane can be manufactured reproducibly on a pilot scale and mounted into fiat-sheet membrane modules of different designs. The operating performance of these modules can be accurately predicted by specifically developed simulation tools, which employ single-gas permeation data as the only experimental input. The performance of membranes and modules was investigated in different pilot plant studies, in which flue gas and biogas were used as the feed gas streams. The investigated processes showed a stable separation performance, indicating the applicability of PolyActiveTM polymer as a membrane material for industrialscale gas processing.

Thermokinetic and conductivity analyzes of the high CO2 chemisorption on Li5AlO4 and alkaline carbonate impregnated Li5AlO4 samples:Effects produced by the use of CO2 partial pressures and oxygen addition

The effect of COpartial pressure was evaluated during the COchemisorption in penta lithium aluminate（LiAlO）, using different COand Opartial pressures in the presence or absence of alkaline carbonates. Results showed that using low PO（0.1） did not affect the kinetic and final COchemisorption process. Moreover, small additions of oxygen（PO= 0.05） into the mixture flue gas, seemed to increase the COchemisorption. Additionally, the presence of alkaline carbonates modified the COcapture temperature range. COchemisorption kinetic parameters were determined assuming a double exponential model where direct COchemisorption and COchemisorption controlled by diffusion processes are considered.Finally, ionic diffusion was analyzed by ionic conduction analysis, where all the gravimetric and ionic measurements were in good agreement showing different diffusion processes depending on temperature.Finally, the oxygen and alkaline carbonate additions have positive effects during the COchemisorption process in LiAlO, and a possible reaction mechanism is presented.