High Amounts Of CO2 Research Articles

Structural evolution of a bituminous coal char related to its synchronized gasification behavior with H2O and/or CO2

This work aims to investigate the structural evolution of the char during gasification under a single or mixed atmosphere of H2O and/or CO2 with the synchronized investigation of the effect of the varying char structure on the gasification reactivity. The experimental char was prepared from a bituminous coal at 1000°C. The changes of the char structure along with the progress of the carbon conversion during gasification were characterized using N2 adsorption, SEM, and Raman spectroscopy. The results revealed that H2O showed a more dramatically change on the char structure than CO2 and two reactants had different reaction pathways. The different pathways of reactants affected the evolution manners of the char structure and different gasification reactivity of char was related to structural evolution. The specific reaction rate between the char and CO2 decreased monotonously with increasing carbon conversion. However, the opposite trends are observed when H2O exist, either H2O alone or the mixtures of H2O and CO2. The char gasification reactivity was under the common effect of physical and chemical structure. In terms of the mixture of H2O and CO2, the significant specific surface area caused by H2O provided more active sites for CO2. The interactions between H2O and CO2 promoted reaction between C and CO2 (C + CO2 → CO) in mixtures of H2O and CO2, leading to higher amount of CO and higher specific reaction rate than calculated.

Seasonal variability of CO2 fluxes at different interfaces and vertical CO2 concentration profiles within a Rhizophora mangrove forest (Can Gio, Viet Nam)

Despite being organic-rich, mangrove soils are usually characterized by low rates of CO2 emissions due to waterlogged conditions, mangroves being thus considered as valuable blue carbon sinks. However, these emissions are highly variable, notably depending on climatic parameters. Can Gio mangrove is a tropical one, being the largest in Vietnam, having being replanted after the war in the late 70's. The main objectives of this study were to quantify the seasonal variability of CO2 emissions at different interfaces (soil-air, water-air, and trunk-air) within a mature Rhizophora stand, and to assess the influence of these emissions on the vertical CO2 concentration profiles in the canopy. CO2 emissions from the soil in the dark were the highest of the different interfaces studied, and were among the highest measured for a mangrove soil, with a mean yearly value reaching more than 270 mmol CO2 m−2 d−1. We suggest that the very high temperatures characterizing Southern Vietnam all year round were responsible for these elevated CO2 emissions. In addition to temperature, the first rainfall pulse of the monsoon resulted in the highest CO2 fluxes both from the soil, reaching up to 500 mmol CO2 m−2 d−1, and from the trunks, reaching almost 230 mmol CO2 m−2 d−1. Because rainfall pulses are usually followed by a period of increasing rates of ecosystem photosynthesis, and a decrease of ecosystem respiration, we measured lower CO2 fluxes during the middle of the wet season. Additionally, it is possible that, during the rainy season, part of the CO2 produced within the soil was exported trough pore-water seepage, which was enhanced because of the higher level of the river. Concerning CO2 emissions at high tide within the Rhizophora stand, the seasonal trend followed the one of precipitation. During the rainy season, estuarine waters are enriched in organic matter and CO2 due to increased runoff in watersheds, and consequently CO2 fluxes from the water column were the highest. However, these emissions were much lower than those from the soil at low tide or from the trunks. Eventually, CO2 concentrations profiles in the canopy varied with the season, the tide, and the night-day alternation. Elevated CO2 concentrations at the root level may imply that prop roots can produce high amount of CO2 but also that they may trap gas emitted from the soil or the water column, possibly acting as physical barriers to air movement. Further studies using eddy-covariance technique should be developed to confirm the hypothesis suggested in this preliminary study.

Experimental Investigation of Diesel Engine Emissions Fueled with Binary and Ternary Blends of Diesel, Biodiesel, and Ethanol

Renewable fuels are a potential substitute for high pollutant fuels attained from conventional sources. Due to the complexity of the combustion process inside the engine, the use of renewable fuels can have a disadvantageous effect on the other emissions of the engine. Most of the researchers have focused on the use of renewable fuel in the internal combustion engine to study their effect on the engine emission but these studies are based on steady-state test and these tests can never correlate with the emission generated by the vehicle in a real-world scenario. The study has been performed to observe the effect of the use of biodiesel, ethanol and diesel blend while running the compression ignition engine in transient condition. Carbon monoxide CO, carbon dioxide CO 2, and oxides of nitrogen NOx were analyzed on a 2.289L diesel engine. The results showed that the use of ethanol in a fraction of 15% produce less amount of CO 2 , and NOx but a higher amount of CO in the exhaust. Use of biodiesel slightly decreases the CO emission in the exhaust while being operated at low and medium speed condition. While NOx and CO 2 emission increases due to the higher oxygen content in the biodiesel as well as due to a higher temperature in the exhaust. The study has also observed that ternary blends have helped in emission reduction while running the engine in transient condition.

Steam Production Options for CO2 Capture at a Cement Plant in Norway

Norcem cement plant, Brevik has the potential to use waste heat to power an amine based CO2 capture plant. Dimensioning the CO2 capture plant according to available waste heat has the possibility to capture around 30 % of the total CO2 emitted from the cement plant. To achieve a higher CO2 capture rate (around 90%), there is a need for extra steam/energy for the capture plant. This work analyses three steam production options i.e., coal fired boiler, natural gas fired boiler, biomass fired boiler. A proposed steam recycle network is simulated in Aspen Hysys v8.6. The results from the simulation provides the input for equipment dimensioning and subsequently in cost estimation. Steam production based on natural gas is calculated to be more economical than steam production based on coal or biomass. Natural gas has the highest boiler efficiency and it also give the lowest amount of CO2 in the flue gas. Although coal has the cheapest fuel cost, it is not the cheapest steam production option. Besides, it gives the second highest amount of CO2 in the flue gas. Other factors that do not go in favor of selecting a coal fired boiler is the pretreatment of coal, the ash handling system and post-treatment of flue gases. Biomass boilers give the highest steam cost that is mainly due to the higher purchase cost of biomass (wood pellets), but an advantage is that the CO2 present in the flue gas is neutral. A cheaper biomass option as a fuel may be an alternative.

Cobalt and copper recovery from the ancient flotation tailings by selective sulfation roast - leaching process

The ancient flotation tailings from Lefke, Cyprus, have a potential for non-ferrous metals such as cobalt and copper from more than 9.5 million tons of reserves containing 0.38% Cu, 0.032% Co, and 22.6% Fe. Recovery of cobalt and copper from these tailings can provide great benefits from economic and environmental perspectives. While the ancient tailings were kept long time in storage in dumps, the characteristics of the material has become different from the common Co and Cu bearing ores. In order to extract these valuable metals, a process involving combination of roasting and leaching was applied in this study. Since this process responded to recovery to some extent, an innovative technique of using Na2SO4 as a promoter during roasting was proposed. Utilizing of Na2SO4 did not provide only higher metal extractions, but also resulted in high selectivity. In the scope of the study, following the determination of the mineralogy and chemical composition of the tailings, certain processes such as direct leaching and sulfation roasting with/without additives before leaching were applied. Since low metal extractions were obtained from direct leaching, a selective sulfation process was applied on the tailings before leaching in order to produce a pregnant solution containing higher amounts of Co and Cu metals by reducing the iron concentration. When sulfation roasting was performed without any additive, the desired selectivity could not be provided, since the sample was considerably oxidized under the atmospheric conditions in the past. Therefore, the usage of Na2SO4 as an additive with the amount of 25% at a roasting temperature of 700?C was tested. Consequently, Na2SO4 improved the sulfation and resulted in higher cobalt (90.1%) and copper (71.2%) recovery during leaching. Beside this, an improvement with a selective sulfation was obtained by combined effect of Na2SO4 addition and temperature, and the iron extraction decreased from 26.1% to 3.9%.

Ce–Sm–xCu cost-efficient catalysts for H2 production through the glycerol steam reforming reaction

The Ce–Sm–5Cu catalyst exhibited the highest H2 selectivity from 40% to 75% while producing the highest amount of CO (97–71%) and the lowest amount of CO2 (3–28%).

Synthesis and characterization of ionic liquid polymer composite with zeolite and its application for carbon dioxide capture

Among the different ways to capture carbon dioxide (CO2), ionic liquid technology is one of the prominent approaches and gained the interest of researchers to improve this technology from time to time. In this study, we have prepared and characterized a novel ionic liquid polymer composite with zeolite and tested its efficiency to capture CO2. The ionic liquid monomer, 1-vinyl-3-ethylimidazolium bis(trifluoromethylsulfonyl)imide [Veim][Tf2N] was polymerized through free radial polymerization process adding zeolite to form poly[Veim][Tf2N] zeolite polymer composite. The synthesized polymer ionic liquid zeolite composite was characterized by FT-IR, FE-SEM and EDX. The formation of polymer ionic liquid zeolite composite was indicated by the presence of zeolite peaks in FT-IR spectra. Additionally, the EDX results were confirmed the presence of zeolite in the prepared composite. Finally, to prove the efficiency of prepared polymer ionic liquid zeolite composite, the adsorption studies have been conducted using CO2 adsorption cell. The results revealed the capability of ionic liquid zeolite polymer composite in adsorbing high amount of CO2 and recorded the highest pressure drop compared to other polymer ionic liquid and monomer ionic liquid materials.

Synthesis of Methanol from Oil- and Gas-Field Flare Gases at the Same Pressure of the Syngas Generation and Methanol Synthesis Steps

A combination of the syngas generation and methanol synthesis steps by pressure is considered to obtain methanol from oil- and gas-fields flare gases. The combined process is thermodynamically analyzed within 700–1100°C and 2–10 MPa for flare gas conversion into syngas. The features of the synthesis of syngas by steam, steam–oxygen, and steam–air conversion are considered. The combined steam conversion of flare gas at 900–950°C and the synthesis of methanol at 230°C together with a total pressure of 3.5–5 MPa make it possible to produce methanol with a yield of up to 1.1 tmethanol/traw and may be recommended for the qualified processing of flare gas into methanol directly on the fields. The synthesis of methanol from syngas with a high amount of CO2 is experimentally verified on copper–zinc catalysts at 230–270°C and 5–8 MPa.

Real-time monitoring of N2O production in a catalytic reaction process using mid-infrared quantum cascade laser

In the context of climate change mitigation, reuse of carbon dioxide (CO2) represents an alternative with important applications in chemical industry and power generation. For this purpose, CO2 must be purified. Combustion processes lead to high amounts of CO2 but still with impurities and also accompanied by toxic gases (mainly NO and CO). A catalytic reduction process of NO (to N2) while oxidizing CO into CO2 is a promising method to purify the CO2. However, nitrous oxide (N2O) with a global warming potential of 300 times greater than CO2 may be a by-product from this process. It is therefore necessary to optimize the chemical reaction conditions to minimize N2O production. A room-temperature continuous-wave (CW) external cavity quantum cascade laser (EC-QCL)-based optical sensor was developed for real-time monitoring N2O production during the whole catalytic reaction process. A well-isolated N2O absorption line, located at 1261.0598 cm−1, of the ν1 fundamental vibrational band was selected for sensitive and selective measurement of N2O concentration by direct absorption spectroscopy. Using a modified-Herriot multi-pass cell with an effective path-length of 50 m, the limit of detection (1σ) of 32.3 ppbv was obtained in 12 s with 1.1% relative uncertainty in measurement precision. N2O productions through the catalytic reduction of NO by CO over Pt/SiO2 catalyst under different temperatures were investigated. High N2O production of up to ∼6.1 ppmv at 190 °C was observed. The optimal reaction conditions for zero N2O production were found at a temperature higher than 340 °C where 47% of NO was converted to N2.

Influence of Molybdenum Loadings on the Properties of MoO3/Zirconia Catalysts

An ideal hydroisomerisation reaction is expected to take place over a bifunctional catalyst, in which a balance between the number of metal sites and acid sites might lead to an optimal performance. In order to assess this relationship and the implications for n-heptane hydroisomerisation, various loadings of molybdenum oxide (1–10 wt%) were impregnated on zirconia with a view to producing samples with a range of acid and metal-like properties. The nature and amounts of the acid sites were determined using quantitative FTIR of pyridine adsorption, while the metal-like properties were determined using CO chemisorption. It was observed that zirconia alone contained only Lewis acid sites (1440 cm−1), while addition of MoO3 generated Bronsted acidity (1536 cm−1). The ratio of Bronsted to Lewis acid sites increased with loadings. Similarly, the amounts of CO taken up by the samples increased with MoO3 loadings; hence, the addition of MoO3 resulted in an improved metal like behaviour. The ratio of Bronsted acid to metal-like sites were found to range between 0.009 and 1.180 on going from 1 to 10 wt% MoO3. The materials were used for n-heptane hydroconversion. The sample with the highest amount of Bronsted acid site, which also consumed the highest amount of CO showed the highest activity. Hence, it could be concluded that the addition of MoO3 improves the Bronsted acid to metal-like site ratio, which resulted in a pronounced improvement in the activity of the samples.

Cultivation strategy to stimulate high carbohydrate content in Spirulina biomass

This study focused on verifying if production of Spirulina biomass with high carbohydrate content is stimulated by reduced supply of nitrogen associated to addition of NaHCO3 or CO2 at different flow rates and times of injection. For this purpose, addition of 0.25 g L−1 of NaNO3 allowed Spirulina to accumulate up to 49.3% (w w−1) of carbohydrates with the highest amount of CO2 (0.3 vvm injected for 5 min). This value reached 59.1% (w w−1) when NaHCO3 was the carbon source. Meanwhile, biomass concentration achieved 0.81 and 0.97 g L−1, respectively. In contrast, protein content was inversely proportional to carbohydrate accumulation in the experiments. Thus, this study represents an important step to define cultivation conditions to enhance carbohydrate content in Spirulina. The carbohydrate-rich biomass could be further fermented to produce bioethanol.

The effect of carbon dioxide on flame propagation speed of wood combustion in a fixed bed under oxy-fuel conditions

This paper presents an investigation of wood combustion in a laboratory-scale fixed bed with an aim of establishing the effect of CO2 environment on flame propagation speed and flame structures. Different oxy-fuel combustion atmospheres in which the composition of O2 in CO2 was varied from 21% to 50% by volume were tested and compared to air-fuel condition. Euler-Lagrange (Computational Fluid Dynamics - Discrete Element Method, CFD-DEM) approach which captures information of individual particle processes is used to model wood conversion in a packed bed. Results show that flame front propagation speed in oxy-fuel atmosphere reduced to 78% of that of the air-fuel condition with similar O2 concentration. For oxy-fuel conditions, propagation speed increased with increase in O2 concentration. The CFD-DEM model agrees very well with experimental values for mass loss, propagation speed and flame front positions. However, peak temperatures are poorly predicted at lower oxygen concentrations. The accuracy of temperature prediction improves at higher oxygen concentrations. During initial and devolatilization stage, mass fraction of tar predicted in CO2 environment are smaller than in N2 environment, while the amount of CO predicted is almost equal in both environments. However, during char combustion stage a high amount of CO is observed in oxy-fuel conditions.

Biological Leaching and Chemical Precipitation Methods for Recovery of Co and Li from Spent Lithium-Ion Batteries

Spent Li-ion batteries (LIBs) are highly rich in cobalt and lithium that need to be recovered to reduce shortages of these valuable metals and decrease their potential environmental risks. This study applied bioleaching using Aspergillus niger strains MM1 and SG1 and Acidithiobacillus thiooxidans 80191 for removal of Co and Li from spent LIB under type 1 and type 2 conditions. Moreover, metal recovery was attempted from the fungal leaching solution by sodium sulfide, sodium hydroxide, and sodium oxalate for Co and then for Li using sodium carbonate. The findings of this work show that metal removal in fungal bioleaching under type 2 system was highly comparable or even better than bacterial or acid leaching. A significant quantity of Co (82%) and Li (100%) dissolution was observed in strain MM1; however, metal solubilization was poor in strain 80191 because only 22% Co and 66% Li solubilized. A high amount of Co precipitated potentially as cobalt sulfide (100%), cobalt hydroxide (100%), or cobalt oxalate ...

Effect of CO2 and crude oil type on the dynamic interfacial tension of crude oil/carbonated water at different operational conditions

Concerns about climate change have persuaded the researchers to examine CO2 injection in the form of carbonated water (CW) into oil reservoir as a safe and effective CO2 storage and enhanced oil recovery process. Although interfacial tension (IFT) between crude oil and injected fluid has a vital role on the displacement of fluids in porous media, the effect of CO2 and crude oil type on the dynamic IFT of crude oil under different operational conditions is not well understood. Accordingly, this study was carried out to assess the effects of temperature, pressure, crude oil type and CO2 on the dynamic IFT of crude oil/CW. To achieve this goal, two types of crude oil were provided from southern Iranian oil reservoirs and dynamic IFTs with CW were measured in a wide range of temperatures and pressures (i.e. temperature range of 30–80 °C and pressure range of 500–4000 psi); the obtained results were compared with the system without CO2. In addition, the adsorption time of carbonated aqueous phase/crude oil, obtained based on the mono exponential decay model, was also compared with unadulterated water/crude oil system. The outcome of this study showed that crude oil type has the most significant effect on the IFT of crude oil/CW compared to pressure, temperature and CO2 content. In more details, the IFT of crude oil/CW can be affected by the amount and type of acidic/basic components in the crude oil as well as pH of the aqueous solution. Besides, the obtained results revealed that the effect of temperature was more considerable on the IFT of the heavy crude oil compared with the light crude oil in both studied aqueous solutions (i.e. unadulterated water and CW). Although the inversion phase temperature was obtained for unadulterated water/studied crude oils at all studied pressures, this phenomenon was not observed for crude oil/CW at elevated pressure, due to the high amount of CO2 at this condition.

Use of crystallite-scale features to predict the reactor-scale performance of a three-way catalyst

A model incorporating the geometry features, transport, and reactions at the crystallite scale is developed to predict the features of a three-way catalyst during cyclic lean and rich conditions. The reactions on the metal crystallite, metal-ceria interface, and ceria surface are considered and the coupling between these reactions and the spillover processes is incorporated. The crystallite-scale model is integrated with the reactor-scale model to predict the experimental concentration profiles for CO oxidation. It is shown that the dependence of oxygen surface diffusivity on temperature can be used to predict the experimental data. It is quantitatively shown that in addition to the active surface area, the interfacial perimeter plays a key role in the spillover and reverse spillover processes. In agreement with the reported trends, the model predicts that the incomplete regeneration of the catalyst at low temperatures is responsible for the low values of oxygen storage capacity. A low but consistent evolution of CO2 occurs for low dispersions in contrast to the high amount of CO2 during the initial few seconds of the rich phase for a high dispersion catalyst. Fundamental insights obtained in the present work are expected to be applicable to other catalysts which involve the spillover effects. To the best of our knowledge, a model which incorporates the geometry features, transport phenomenon and reactions at the crystallite scale and its integration to predict the reactor-scale data under flow conditions for a three-way catalyst has not been reported elsewhere.

Investigation on the low-temperature pyrolysis of automotive shredder residue (ASR) for energy recovery and metal recycling

The automotive shredder residue (ASR) or shredder light fraction (SLF) is the remaining fraction from the metal recovery of end-of-life vehicles (ELVs). While processes for metal recovery from ELVs are well developed, the similar process for ASR remains a challenge. In this work, low-temperature pyrolysis of the ASR fraction was investigated under the assumption that a low temperature and inert environment would enhance the metal recovery, i.e. the metals would not be further oxidised from their original state and the organic material could be separated from the metals in the form of volatiles and char. Pyrolysis experiments were performed in a tube reactor operating at 300, 400 and 500 °C. The gas and oil obtained by pyrolysis were analysed by micro-GC (micro-Gas Chromatography) and GC/MS (Gas Chromatography/Mass Spectrometry), respectively. It was found that the gas produced contained a high amount of CO2, limiting the energy recovery from this fraction. The oil consisted of a high concentration of phenolic and aromatic compounds. The solid residue was crushed and fractionated into different particle sizes for further characterization. The pyrolysis temperature of 300 °C was found to be insufficient for metal liberation, while the char was easier to crush at tested temperature of 400 and 500 °C. The intermediate temperature of 400 °C is then suggested for the process to keep the energy consumption low.

The Relationship Analysis between Motorcycle Emission and Road Facilities under Heterogeneous Traffic Situation

Motor vehicles have long been a source of pollution in many major cities in the world, including Indonesia. The increasing of the motor vehicle on the road leads to the rising of air pollution that exhausted by the vehicles as consequently. This research is intended to analyze the relationship between motorcycle emission and road facilities for each kind of road facilities in four different arterial road types. This study is quantitative research in which data collection is done directly in 4 types of road such as 2/1 UD, 4/1 UD, 4/2 D, and 6/2 UD in Makassar using motorcycle the Gas Analyzer Portable Measurement System and GPS emission test for speed tracking. The results are the emission tend to increase in road facilities where JS3TB (unsignalized junction) has the highest amount of CO and CO2 emission compared to other types.

A Cu(ii) metal-organic framework with significant H2 and CO2 storage capacity and heterogeneous catalysis for the aerobic oxidative amination of C(sp3)-H bonds and Biginelli reactions.

A Cu(ii) metal-organic framework, {[Cu2(L)(H2O)2]·(5DMF)(4H2O)}n (1), has been synthesized using an angular tetracarboxylic acid ligand (H4L) incorporating both trifluoromethyl (-CF3) and amine (-NH2) groups. Notably, the framework possesses high water and thermal stability. At atmospheric pressure, the activated framework 1' exhibits substantially high amounts of CO2 (35.5 and 20.8 wt% at 273 and 298 K respectively) and H2 (1.72 wt% at 77 K) adsorption. Also, 1' exhibits excellent catalytic activity for the condensation-cyclization reaction between 2-benzoyl pyridine and different benzylamines via oxidative amination of the C(sp3)-H bond to form 1,3-diarylated imidazo[1,5-a]pyridines under mild aerobic conditions. In addition to this, 1' shows excellent heterogeneous catalytic activity in Biginelli reactions. The solid catalyst could be recycled several times without significant loss in the catalytic activities.

A Green GIS Solution against Air Pollution in the Province of Bergamo: The Paulownia Tree

The paper describes a GIS approach to identify the most suitable areas for growing the Paulownia tree in the Province of Bergamo; this work will become the subject of a dissertation thesis at the School of Engineering of the University of Bergamo. Paulownia is quite an ancient tree, well known especially in the far east countries, for its wonderful flowers and the quality of the wood which is a source of certain profit. The paper is focused on the employment of the Paulownia tree against air pollution, since its big leaves absorb high amounts of CO2 in the atmosphere and can capture the small particles of pollutants in the air ten times more than any other tree species. First, the analysis identifies the most favourable areas for its growth in the Province of Bergamo. Secondly, among the latter, the analysis detects the strategic areas for its growth near the most polluted zones. Finally, a quantitative evaluation is carried out about the trees contribution against pollutants in the atmosphere.

Mechanical properties of fly ash geopolymer mortar reinforced with carbon fibers

Portland cement industry releases high amounts of CO2, so efforts have been made for alternative binders. Geopolymers are one of the highlighted elective binders. The aims of this study are to produce fly ash Geopolymer boards reinforced with carbon fibers and investigate the mechanical properties of several blends of fly ash Geopolymer mortar reinforced with carbon fibers (FGC). Carbon fibers (CF) were added at different percentages (WF) of 0.2%, 0.5%, 1%, and 1.5% by weight. The sodium hydroxide condensation of 8 molars, sodium silicate to sodium hydroxide weight ratio of 2.0, the alkaline liquid/binder proportion of 0.47 and the dry heat curing of 70°C for 24 hours were utilized as a piece of blends. Fresh and hardening state properties such as Flow capacity, flexural strength and compressive strength, and physical properties such as bulk density were determined from the 3-day FGC samples after the curing process. The results obtained from this study, show that the uses of CF were significant in improving the compressive and flexural strength due to the bonding characteristics of fibers with Geopolymer pastes. Then again, the used of CF results in slightly decrease of the bulk density. The optimal compressive and flexural strength outcomes were at weight percentage 1% of CF.