122 research outputs found
Decarbonization of the Gas Processing and Chemical Plants: The Path for Technology Commercialization
No full textAbstract: Natural gas has emerged as a crucial clean fuel source to address escalating global energy demands, projected to increase by 40% by 2030 and 15-16% by 2050 compared to 2014 and 2023, respectively. Nevertheless, the sustainability of natural gas as a source of energy and chemicals depends mainly on our success in decarbonizing the industry. I will share examples of decarbonizing midstream and downstream sectors of the industry in my presentation while identifying CO2 utilization routes. Dry reforming of methane (DRM) offers an avenue for converting carbon dioxide (CO2) and methane (CH4)—the two major greenhouse gases—into syngas, a vital chemical precursor. However, DRM is constrained by high energy demands, catalyst deactivation, and an unfavorable H2/CO ratio. My research team developed a novel technology with a dual-reactor system that produces multi-walled carbon nanotubes (MWCNTs) and syngas as products. CARGEN® offers at least 65% CO2 conversion at 50% of the energy demands of DRM. Utilizing modeling and experimental studies, we scaled up CARGEN® from the milligram scale to the multi-gram scale and, ultimately, to the multi-kilogram scale of MWCNT production. Ultimately, the outcome of this study encourages CARGEN-based chemicals and refinery plants that co-produce syngas, hydrogen, and MWCNTs from CO2 and natural gas as an integrated decarbonization solution. The technology is currently moving toward the commercialization phase.
Another example is the direct synthesis of dimethyl carbonate (DMC), which is considered the most promising route from a green chemistry perspective. This route generates water as the only byproduct in the reaction between CO2 and methanol. My research team worked with Shell to scale up this technology and evaluate its potential for commercialization.
Finally, my research team developed two new quantitative parameters to evaluate the probability of CO2 fixation for decarbonization technologies. The greenhouse gas reduction, sustainability, and economics framework (GASEF) assess commercial viability by simultaneously analyzing a CCU technology’s CO2 fixation (CO2Fix) potential and its economic benefits.
Biography: Elbashir is the director of Texas A&M’s Engineering Experiment Station Gas & Fuels Research Center (GFRC), a major research center involving 30 faculty members from the College Station and Qatar campuses of Texas A&M University (http://gfrc.tamu.edu/). He is a professor of chemical engineering and serves on the Qatar and College Station campuses. He has extensive research and teaching experience from four countries worldwide, including his previous position as a researcher at BASF R&D Catalysts in Iselin, New Jersey. His research focuses on designing advanced reactors and catalysts for natural gas and CO2 conversion and decarbonization. He has established several unique global research collaboration models between academia and industry, with research funds exceeding seventeen million dollars. He holds several U.S., European, and international patents and many scientific publications. The scholarship of his research activities has been recognized by awards from BASF Corp., Texas A&M University & TEES, the American Institute of Chemical Engineers, Shell, ORYX GTL Co., the Qatar Foundation, and others. Elbashir was elected as a Fellow of the AIChE in August 2023, a member of the Sudan National Academy of Sciences (SNAS) in 2022, and its general secretary in February 2024.Illinois Sustainable Technology Cente
DFT Study of Copper-Nickel (111) Catalyst for Methane Dry Reforming
No full textNo one can deny that the increasing energy demand -due to world population booming- and climate change are two major challenges facing humanity in the current century. Climate change phenomenon is basically related to green house gases (GHGs) emissions which result in increasing temperature of earth. Among GHGs, COV2 is the major contributor in global warming while CHV4 is considered a major energy source as the main component of natural gas. Dry reforming of methane (DRM) achieves utilization of both COV2 with CHV4 by producing syngas which can be converted into valuable compounds. Thus, DRM is a currently a hot subject in both industrial catalysis and environmental research. The applicability of DRM in industry is hindered by its high energy demand and coke formation on catalyst surface which leads to rapid catalyst deactivation. Nickel catalyst is well-known for an activity comparable to those of the expensive and abundant noble metals. However, pure Ni catalyst can suffer from severe coke formation at the elevated temperatures required for DRM reaction. To reduce coke formation, Nibimetallic catalysts are examined as they have shown reasonable activity and reduced carbon deposition. Several nickel-transition metals bimetallic catalysts showed their potential for coke resistance and improved activity. While the synergetic effects of CoNi-bimetallic catalyst is found to be due to its oxophilicty, Ni-Fe catalyst activity is attributed to redox system formation. However, Cu behavior of coke resistance and activity enhancement is still not well-defined at molecular level at the time of this study.
This study uses DFT (Density Functional Theory) computational methods to evaluate DRM reaction on Ni2Cu (111) bimetallic catalyst. The study will reveal how different species of elementary reactions are adsorbed on catalyst surface, explore the reaction mechanism and investigate the role of atomic oxygen as well as hydroxide species in carbon removal and catalyst stability in presence of Cu in the Ni-Ni network. The results will also explain the dominant reaction pathway by calculating the activation energy barriers of different elementary reactions and contribute to design of new stable and coke-resistant catalyst that can be used for DRM on the industrial scale
Modeling Catalyst Activity and Selectivity for the Gas to Liquid Technology (GTL)
No full textThe activity and selectivity of catalytic systems used in gas to liquid (GTL) technology have been studied. In the activity study, seven catalytic systems that were used in the dry reforming of methane have been analyzed. The generalized power law expression (GPLE) model was used to fit the activity profile and predict mechanism of catalyst deactivation. The first and second order GPLE fit well to the experimental data with regression factor (R2 ) ranged between 0.95 and 0.99. Also, it was possible to deconvolute the deactivation mechanism into two main causes, fast deactivation by sintering and the slow deactivation by carbon deposition. In the selectivity study, a detailed kinetics model was developed to estimate the product distribution of the cobalt catalyst in the supercritical fluid phase of the Fischer-Tropsch synthesis reaction (SCF-FTS) up to carbon number 15. The adopted mechanism to describe the reaction network is the alkyl mechanism. Six experimental runs were conducted, corresponding to three temperature levels of experimental data (230���, 240��� and 250���), three total pressures (45 bar, 65 bar, and 80 bar) to capture the critical and near critical condition, (H2:CO=2:1) and gas hourly space velocity (GHSV) of 500 (1/h).
To estimate the model parameters a genetic algorithm code was developed in MATLAB. The model results showed that the maximum mean absolute relative residual (MARR) was 35.32%. Moreover, the model was able to predict the n-paraffin formation rate and Anderson-Schulz-Flory (ASF) product distribution with acceptable range of error
Simulation of Fischer-Tropsch Fixed-Bed Reactor in Different Reaction Media
No full textThe continuous increase in the global demand for a cleaner energy source has instigated much interest in converting natural gas to ultra-clean fuels and value-added chemicals. Fischer-Tropsch synthesis (FTS) is a key technology for converting syngas, produced from coal, biomass or natural gas, into a variety of hydrocarbon products. Although this technology has been around for decades, commercial development remains relatively slow and limited to use of few reactor configurations (e.g. fixed-bed reactor and slurry-bubble column reactor).
On the lab-scale, supercritical solvents were utilized in FTS as a reaction media since they have the advantages of both the gas-phase reaction (fixed-bed reactor) and the liquid-phase reaction (slurry-bubble column reactor), while simultaneously overcoming their limitations. This work focuses on modeling the behavior in the reactor bed (���macro-scale��� assessment) and then zooming into the catalyst pellet itself (���micro-scale��� assessment).
The aim of this research is to simulate the heat and mass transfer behavior inside the reactor bed, identify typical conditions that look at the existence and absence of both mass and heat transfer limitations, and to quantify the role of the main controlling parameters on the overall behavior of the reactor bed and on the catalyst effectiveness factor. An often used mathematical model of the fixed-bed reactor was applied to simulate the concentration and temperature profile simultaneously based on the appropriate mass and heat balances at both scales. A second-order ordinary differential equation was used for a spherical pellet in the radial coordinate for both mass and heat balances, while a one-dimensional steady state pseudo heterogeneous model was used for the reactor bed modeling in the axial direction. In addition, in both models the mass balance equation was expressed in terms of fugacity to account for the non-ideal behavior of the reaction mixture in the SCF-FTS. The thermodynamic properties of the mixture were estimated using the Soave-Redlich-Kwong equation of state (SRK-EOS).
The simulation results of this study showed a high temperature rise in the gas- phase FTS relative to that in the SCF-FTS under a comparable reaction conditions. Carbon monoxide conversion was considerably higher in the SCF compared to the gas- phase reaction. The effect of the particle size on the overall catalyst effectiveness factor was also investigated in both reaction media
Removal of Mercury From Water Using Iron(II) Sulphide Nanoparticles and Ultrafiltration Membrane
No full textIn this study, reactive nanoparticulate FeS was used to remove Hg(II) from water with an ultrafiltration system. A dead-end ultrafiltration (DE/UF) system was developed to remove Hg(II)- contacted FeS from water in the presence of 0.01M anions (Cl- , NO3 - , SO4 2- ) and 1 mg/L HA in non-stirred mode using regenerated cellulose membrane. The DE/UF stirred mode was applied to evaluate the ���shear effect��� on the rejection of Hg-contacted FeS. Batch tests reveal that complete Hg(II) removal was achieved in 10 minutes in the presence of anions and 60 minutes in the presence of HA. A cross-flow ultrafiltration (CF/UF) system was implemented to examine continuous removal of Hg-contacted FeS in the presence of 0.01 M anions using 1000 kDa polyethersulfone membrane. Experimental results showed that in the presence of anions, higher Hg(II) removal was observed compared to Hg(II) and FeS alone with slight decrease in pH and increased flux decline. The highest Hg(II) removal was achieved in the presence of HA with no pH effect despite significant impact on membrane permeability and slight Fe released during the desorption tests. The DE/UF stirred mode system exhibited reduced cake formation leading to less flux decline. In terms of membrane pore size, 100 and 300 kDa exhibited significant flux recovery despite greater flux decline compared to 30 kDa. Overall, the developed ultrafiltration systems produced chemically stable Hg-contacted FeS particles that can be reused and disposed safely in the environment. In the DE/UF system nonstirred mode, Hg-contacted FeS achieved complete additional Hg(II) removal. However, the DE/UF stirred mode and the CF/UF system exhibited decreased additional removal capacity. These could be due to chemical variations in the FeS particles caused by the shear effect and tangential flow on the Hg(II)-contacted FeS. SEM/EDS analyses demonstrate that the Hg loading on the membrane was higher in the presence of humic acid and anions. These findings present fundamental data that could be applied in the advancement of Hg(II)-contaminated water treatment using low cost FeS adsorbents and can serve as a guideline for continuous treatment of other toxic inorganic chemicals
Utilization of Supercritical Fluids in the Fischer-tropsch Synthesis over Cobalt-Based Catalytic Systems
No full textFischer-Tropsch synthesis (FTS) holds great potential for the production of ultra-clean transportation fuels, chemicals, and other hydrocarbon products through the conversion of readily available syngas (CO/H2) from abundant resources (coal, natural gas, and biomass). Utilization of supercritical phase in FTS as a medium that has superior properties (liquid-like density and heat capacity, and gas-like diffusivity) represents a new challenge to the 80-years old FTS technology. The objective of this research is to establish optimum operating conditions for FTS within the supercritical region that would maximize the production of value added chemicals and middle distillate hydrocarbons (gasoline fuel, jet fuel, and diesel fuel fractions) and at the same time minimize the production of methane and carbon monoxide. Chapters 3-5 of this dissertation are designed to examine the effects of supercritical fluid (SCF) (n-pentane or hexane) on FTS over an alumina supported cobalt catalyst in a fixed-bed-reactor. The influence of reaction conditions (such as temperature (210-260 ?C), pressure (20-80 bar), syngas feed ratio (H2/CO ratio of 0.5-2), contact time and space velocity (50-150 sccm/gcat)) on the FTS activity, selectivity, and hydrocarbon product distributions in the supercritical fluids (SCF) media was studied. Our results show that the adjustable thermophysical properties of the SCF significantly impact the FTS reaction performance and in most cases the SCF-FTS operations yield higher activity and better selectivity towards the most desired products compared to conventional gas-phase FTS operations. An excellent opportunity to maximize the production of desired fuel fractions, through a simple tuning process of the reaction environment from liquid-like properties to vapor-like properties, can be achieved in the SCF-FTS conditions as discussed in Chapter 4. An approach to understand the enhanced chain growth probability in SCF-FTS conditions is reported in Chapter 5. This phenomenon was attributed to the enhanced ?-olefins incorporation in the chain growth process. Chapter 6 covers a preliminary examination of the kinetics of the FTS reactions under high-pressure high-temperature conditions in both conventional gas-phase FTS and supercritical hexanes FTS (SCH-FTS). Our findings illustrate that the classical surface reaction kinetics model fails to predict the rates in the SCH-FTS. Our findings also show that the cobalt-based catalytic systems show excellent stability in terms of activity and selectivity as well as their structure under the SCF-FTS conditions for relatively long time-on-stream (up to 13 days). The influence of the cobalt-based catalyst characteristics on the FTS performance in both SCH-FTS and conventional gas-phase FTS is addressed in Chapters 7 and 8
A Path to the Formulation of New Generations of Synthetic Jet Fuel Derived from Natural Gas
No full textCharacterization of jet fuels obtained from sources other than crude oil is a modern area of research that is developing continuously to replace available petroleum-based fuels with ���drop-in��� alternative fuels. Therefore, reliable composition-property relations are developed to correlate the hydrocarbon compositions of formulated synthetic fuels with their properties to be certified for aviation commercial use.
Intensive studies have been initiated at Texas A&M University Qatar in collaboration with industry and academia to study synthetic jet fuels derived from natural gas. These studies are being implemented at its Fuel Characterization Lab where the most advanced testing equipment is used and strict Quality Management and safety systems are followed.
This study is divided into two tracks. The first track is focused on conducting experimental investigations using in-house formulated synthetic jet fuels derived from natural gas via Gas-to-Liquid technology and Fischer-Tropsch chemistry. Throughout this research work, these fuels will be referred to as Synthetic Paraffinic Kerosene (SPK). These experimental investigations activities are composed of three phases: the first phase focuses on the influence of SPK building blocks (paraffinic hydrocarbons) on fuels��� properties, the second phase concerns evaluating the role of aromatics and cyclo-paraffins on properties, and the third phase studies the influence of mixing SPK with conventional Jet A-1 derived from crude oil. All of the aforementioned experimental investigations are aimed at building an experimental data bank to assist the efforts of the formulation of new generations of SPKs that meet aviation industry standards. On the other hand, the second track is directed towards the development of mathematical correlations for four properties of high importance to SPK certification. These correlations aim at optimizing fuel composition whereby major physical/chemical properties of ASTM D1655 are met at the lowest cost of composed fuel.
The primary findings of this study showed that GTL derived SPK paraffinic constituents can improve certain properties while affecting others negatively, and emphasizing the necessity of aromatics in improving specific properties. Further studies compensating the absence of aromatics and sulfur through blended Jet A-1 revealed a practical solution through jet fuels optimization based on cost and technical effective manners
A Systemic Approach To Understand Relationship Between Compositions Of Gtl Derived Synthetic Fuels And Their Properties
No full textCharacterization of Synthetic Gas-to-Liquid Jet Fuel Blends and Properties Correlation with Hydrocarbon Groups
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