Journal of The Energy Institute最新文献

Pyrolysis is a thermo-chemical conversion method for harmless and resource utilization of sewage sludge, which gives carbon-containing products with high added value and benefits for GHG reduction towards “carbon peaking and carbon neutrality” goals. In this work, co-pyrolysis of sewage sludge and poplar wood was studied to investigate the effects of the wood blend ratio and the volatile-char interactions on the pyrolysis product characteristics. It was found that the synergistic effect during co-pyrolysis could enhance the production of aromatic hydrocarbons but inhibit the formation of nitrogen-containing and phenolic compounds. Meanwhile, the aromaticity of the char increased with increasing the wood blend ratio, resulting in an enhanced quality of the char. The volatile-char interactions could facilitate the cracking of large molecules in volatiles into small-molecule gases, leading to an increase in the gas yield of 0.6–14.6 %, and especially the H₂ yield of 16.2–53.8 %, as compared to the case without interaction in the experiment. The char yields hold fairly constant but the physicochemical structure of the char changed significantly with the interactions. Specifically, the O-containing functional groups on the char surface decreased significantly with increasing aromaticity and stability. More importantly, the total phosphorus content of char was increased by 11.3–33.6 %, as compared to the case without interaction, with the enhanced conversion of non-hydroxyapatite phosphorus to hydroxyapatite phosphorus. The interaction can increase bio-availability of the phosphorus and make biochar to be a better organic fertilizer in application.

As a renewable energy with zero carbon emission, the utilization of biomass has attracted widely studied. One of the most effective methods is to gasify the biomass into high-quality gas fuel. In the recent years, the majority of research on biomass gasification is conducted in the laboratory. However, it lacks the research in engineering application scale. In this work, a biomass gasification-combustion plant was designed and built to provide the industrial steam with a rate of 30 t/h for a food industrial park. The agricultural and forestry waste biomass was gasified in a gasifier, and then the product gas combusted in a boiler to supply the steam. The characteristics of the product gas from the gasifier were studied. The corrosion and pollutants in the combustion process were investigated. In the gasification process, the main components of the product gas are CO, H₂ and CH₄. CO and H₂ account for 29.55 vol%-30.56 vol% and 11.65 vol%-15.35 vol%, respectively. The calorific value of the product gas is 5.88–6.29 MJ/m³. The tar concentration is 110.58–155.07 g/Nm³. At the outlet of the boiler, the concentration of the filterable particulate matter is 300.25 mg/Nm³, and the particle size is concentrated at 1.00–2.50 μm. The concentration of the condensable particulate matter (CPM) is 157.14 mg/Nm³, and the proportion of water-soluble ions in CPM is 86.36 wt%. The concentration of Cl⁻, SO₄^2-, NH₄⁺ and Na⁺ in CPM is relatively high, with the values of 28.83 mg/Nm³, 10.29 mg/Nm³, 7.46 mg/Nm³, and 5.06 mg/Nm³, respectively. During the half-year running, the ash deposition and corrosion were detected in the boiler heating surface and the economizer. The ash deposit in the boiler is mainly composed of the sulfate and silicate, such as CaSO₄, Zn₂SO₄, Na₂SO₄ and K₃Na(SO₄)₂. The ash deposit in the economizer is primarily composed of the sulfate and a small amount of alkali metal chloride. The flue gas reaches the emission requirement after passing through the pollution control devices and can be discharged into the atmosphere.

With the combination of stepwise dechlorination and co-pyrolysis techniques, this study conducted polyvinyl chloride (PVC) dechlorination experiments and co-pyrolysis experiments of poplar wood (PW) with dechlorinated polyvinyl chloride (DPVC) by thermogravimetric analysis and a fixed bed reactor. Stepwise pyrolysis effectively removed Cl from PVC with a dechlorination efficiency of 99.84 % at 360 °C for 30 min. Thermogravimetric tests and thermokinetic variables were employed to describe the co-pyrolysis process's thermodynamic behavior, where co-pyrolysis significantly diminished the activation energy of the initial pyrolysis stage (9.65–21.62 kJ/mol) and increased the reaction rate (0.02–0.09 %/°C). The synergistic effect of co-pyrolysis enhanced the yield and quality of liquid oil and reduced the solid residue rate, with the maximum change in solid residue rate (−2.36 wt%) occurring at PW:DPVC = 3:7. The optimal conditions for the synergistic effect are a raw material ratio of 3:7 at 500 °C. Co-pyrolysis efficiently reduced the content of oxygen-containing compounds of phenols, ketones, and acids in oil, and elevated the selectivity of aromatics. The research methods avoid the drawbacks of bio-oil and plastic oil and improve the quality of pyrolysis oil in a concise and efficient manner, which provides some new ideas for the resource and clean utilization of municipal waste.

Acetic acid dry reforming (ADR) is a promising route for sustainable H₂ generation. However, coke inhibition during ADR is the main challenge and not resolved by using suitable promoted catalysts. In this work, Ce promotion on 10%Ni/Al₂O₃ catalysts with 1-5 wt%Ce was evaluated for ADR at varied temperatures of 923–998 K and stoichiometric feed in a fixed-bed rig. CeO₂ addition of 1–3% enhanced metal dispersion, and surface area whilst basic CeO₂ character significantly boosted the concentration and density of basic sites on catalysts. Particularly, the CO₂ uptake of promoted catalysts was about 2.49–3.73 times greater than that of counterpart sample. CH₃COOH and CO₂ conversions were enhanced with rising Ce loading and the highest reactant conversions were observed at 3 wt%Ce. The improved adsorption of acidic CH₃COOH and CO₂ molecules due to increasing amount of basic sites as well as redox attributes of CeO₂ promoter could be responsible for the enhancement in ADR activity and yield of H₂ and CO. The mechanistic two-step pathway for coke suppression induced by CeO₂ promotion was elaborated in this work. Generally, carbonaceous species formation on 3%Ce–10%Ni/Al₂O₃ was considerably reduced about 1.6–2.0 times. H₂/CO ratio varied from 0.59 to 0.65 relying on ADR temperature over 3%Ce–10%Ni/Al₂O₃. These H₂/CO values, two times higher than theoretical H₂/CO ratio in ADR, are compatible for downstream gas-to-liquid processes to selectively yield high molecular weight olefins. Water formation rate increased from 8.67 × 10⁻⁶ to 4.71 × 10⁻⁵ ${\text{mol}}_{H_{2}O}$ g_cat⁻¹ s⁻¹ with rising temperature within 923–998 K on 3%Ce–10%Ni/Al₂O₃.

This research delves into the field of fast hydropyrolysis of mixed municipal solid waste (MSW), with the goal of understanding product distribution and interactions in a hydrogen-rich condition. Through experimental investigations on MSW and its components, this study thoroughly examines the impact of pyrolysis temperature and gasification atmosphere (30 % H₂+30 % CO+20 % CO₂+20 % H₂O) on the yields and distribution of the three-phase products. As the temperature increases, the gas yield gradually increases, while the yields of tar and char gradually decrease. The introduction of a hydrogen source increases the methane content in the combustible gas, which generally reaches its maximum at 850 °C, and promotes aromatic formation in tar, making aromatics the main component of pyrolysis oil. Notably, aromatics have the highest-octane number in gasoline. This study highlights gasification as a promising technology for converting organic waste into valuable fuel, advancing waste management and energy recovery.

By reasonably controlling the lattice oxygen of oxygen carrier (OC), the biomass chemical looping gasification (CLG) technology can convert biomass into syngas dominated by H₂ and CO, which is a prevalent topic in the world. However, in practical applications, the mechanism underlying OC agglomeration induced by alkali and alkaline earth metals (AAEMs), along with effective countermeasures, remain ambiguous. In this paper, AAEM elements were added to the biomass after pickling to explore the effects of K, Na, Ca, and Mg on agglomeration. The results indicated that with the increase of K and Na additions from 0.5 % to 18 %, the deformation temperature (DT) of spent OC decreased, leading to a marked intensification of agglomeration, with degree of agglomeration increases from 2.88 % and 1.74 % to 17.44 % and 13.91 %, respectively. In contrast, with the increase of Ca and Mg additions from 0.5 % to 18 %, the DT of spent OC increased, and the degree of agglomeration remained lower than that of K and Na, with values ranging only from 1.03 % and 0.95 % to 11.17 % and 2.66 %, respectively. Besides, with augmented alkali metal chloride addition, the amount of low melting point aluminosilicates formed from SiO₂ and Al₂O₃ increased, further exacerbating the OC agglomeration.

We have reported the importance of biomass ratio in the co-pyrolysis of waste plastics to regulate the aromatic content and oxygenated compounds in hydrocarbon-rich fuels for enhancing engine performance. The study revealed that changing biomass to plastic ratio can control aromatic compositional change. The obtained product was characterized using different instrumentation techniques, such as NMR, FTIR, GCMS, etc., to identify the hydrocarbon types in the liquid product. Results revealed that it contains C₈-C₂₄ range carbon compounds with dominating aromatics compounds, as confirmed by ¹H NMR and FTIR analysis. The pyro-oils contain different hydrocarbons: olefins, paraffin, aromatics, esters, and alcohols. It was observed that the presence of biomass in co-pyrolysis produces oxygenated compounds up to ∼12.08 % and also enhances calorific value up to 55.4 MJ/kg from 48.3 MJ/kg due to the presence of longer hydrocarbon chains of esters in pyro-oil. Biomass co-pyrolysis also improved the fuel properties such as pour point (<-25°C) and 4°C increment in flash point. Engine performance showed that blending biomass pyro-oil obtained from B25PS75 reduced fuel consumption and increased BTE.

It is crucial to study the Fe-O coordination environment due to oxygen defects for elucidating the dynamic active center during CO chemical looping combustion with hematite. In this work, Fe-based oxygen carriers with varying oxygen vacancy concentrations were firstly synthesized by direct thermal decomposition of ferric nitrate and subsequently evaluated through fixed-bed experimentation. It was showed that the reactivity of oxygen carriers produced by calcination at 700 °C exhibited a higher CO conversion rate due to the moderate oxygen vacancy concentration. Then, density-functional theory (DFT) calculations were conducted to examine the impact of oxygen vacancies. The results indicated that the formation of oxygen vacancies exhibited a proximity effect, resulting in the emergence of various Fe-O coordination environments. The low coordination number of Fe-O enhances the reactivity of the lattice oxygen and significantly lowers the activation energy barrier for the oxidation of CO to CO₂. Furthermore, the effect of oxygen vacancies on the migration of bulk phase oxygen was also investigated. It was shown that the migration barriers of bulk oxygen increased with the concentration of oxygen vacancies, resulting in a reduction in the oxygen supply rate. Moderate concentration of oxygen vacancies facilitates CO oxidation by aligning surface catalysis with the oxygen migration rate. This evidence suggests that the Fe-O coordination environment and oxygen vacancy concentration serve as key factors in controlling in controlling CO oxidation over Fe-based oxygen carriers.