Advanced studies of catalytic upgrading of heavy oils

Heavy oil and bitumen are known to constitute high-boiling molecules which gives them characteristic high viscosity, high density/low API gravity, low yields of fuel distillates, and high heteroatom content compared to light oil. Upgrading therefore refers to the breaking down of heavy oil into oil with similar characteristics as light crude oil. The toe-to-heel air injection (THAI) and its catalytic add-on CAPRI (CAtalytic upgrading PRocess $In-situ$) were developed to achieve this objective down-hole. In this study, the CAPRI process was explored with the objective of controlling catalyst deactivation due to coking while increasing the extent of upgrading. The effects of reaction temperature and weight hourly space velocity on the extent of upgrading were studied in the range of 350-425$^o$C and 9.1-28 h$^-$$^1$, respectively. In order to control premature deactivation of the catalysts due to coke and metal deposition, the following were investigated activated carbon guard-bed on top of the catalyst bed, hydrogen-addition, steam environment as a source of hydrogen-donor, and nanoparticulate catalyst. It was found that high reaction temperature of 425$^o$C and lower WHSV (9.1 h$^-$$^1$) improved the cracking as well as increase API gravity (~3-7$^o$), viscosity reduction of (81.9 %), demetallisation (9.3-12.3 %), desulphurisation (5.3-6.6 %), and higher yield of fuel distillates, respectively compared to upgrading at 350 and 400$^o$C. In spite of the improvement in produced oil at 425 $^o$C, the carbon-rejection was high (51-56.6 wt.%) compared to (42-47.8 wt.%) and (48-50.3 wt.%) when reaction was carried out at 350 and 400$^o$C for 25 hours operations

A Kinetic Model of Furfural Hydrogenation to 2-Methylfuran on Nanoparticles of Nickel Supported on Sulfuric Acid-Modified Biochar Catalyst

Lignocellulosic biomass can uptake CO2 during growth, which can then be pyrolysed into three major products, such as biochar (BC), syngas, and bio-oil. Due to presence of oxygenated organic compounds, the produced bio-oil is not suitable for direct use as a fuel and requires up-grading via hydrodeoxygenation (HDO) and hydrogenation. This is typically carried out over a supported metal catalyst. Regarding circular economy and sustainability, the BC from the pyrolysis step can potentially be activated and used as a novel catalyst support, as reported here. A 15wt% Ni/BC catalyst was developed by chemically modifying BC with sulfuric acid to improve mesoporous structure and surface area. When compared to the pristine Ni/BC catalyst, sulfuric activated Ni/BC catalyst has excellent mesopores and a high surface area, which increases the dispersion of Ni nanoparticles and hence improves the adsorptive effect and thus catalytic performance. A liquid phase hydrogenation of furfural to 2-methylfuran was performed over the developed 15wt% Ni/BC catalyst. Langmuir–Hinshelwood-Hougen-Watson (LHHW) kinetic type models for adsorption of dissociative H2 were screened based on an R2 value greater than 99% demonstrating that the experimental data satisfactorily fit to three plausible models: competitive (Model I), competitive at only one type of adsorption site (Model II), and non-competitive with two type of adsorption sites (Model III). With a correlation coefficient greater than 99% between the experimental rates and the predicted rate, model III, which is a dual-site adsorption mechanism involving furfural adsorption and hydrogen dissociative adsorption and surface reaction, is the best fit. The Ni/BC catalyst demonstrated comparative performance and significant cost savings over previous catalysts, a value of 24.39 kJ mol-1 was estimated for the activation energy, -11.43 kJmol-1 for the enthalpy of adsorption for H2, and -5.86 kJmol-1 for furfural. The developed Ni/BC catalyst demonstrated excellent stability in terms of conversion of furfural (96%) and yield of 2-methylfuran (54%) at the fourth successive experiments. Based on furfural conversion and yield of products, it appears that pores are constructed slowly during sulfuric acid activation of the biochar

Eggshell and Seashells Biomaterials Sorbent for Carbon Dioxide Capture

This review aims to explore the application of natural and renewable bioceramics such as eggshell and seashells in carbon dioxide (CO2) capture from power plant flue gas. CO2 capture, utilisation and storage (CCUS) is considered a means to deliver low carbon energy, decarbonising industries, power plants and facilitates the net removal of CO2 from the atmosphere. The stages involved include CO2 capture, transport of the captured CO2, utilisation and secure storage of the captured CO2. This chapter reports the use of eggshell and seashells biomaterials as an adsorbent to separate CO2 from other gases generated by power plants and industrial processes. The capture of carbon dioxide by adsorption is based on the ability of a material to preferentially adsorb or carbonate CO2 over other gases. In light of this, calcined eggshell and seashells biomaterial rich in calcium carbonate from which calcium oxide (94%) can be obtained have demonstrated a strong affinity for CO2. These biomaterials are abundant and low-cost alternative to zeolite, activated carbon and molecular sieve carbon. The mechanism of CO2 capture by eggshell and seashells derived CaO adsorbent comprises of a series of carbonation-calcination reactions (CCR): calcium oxide (CaO) reacts with CO2 resulting in calcium carbonate (CaCO3), which releases pure CO2 stream upon calcinations for sequestration or utilisation, and as a consequence, the biomaterial is regenerated. Findings reveal that these biomaterials can hold up to eight times its own weight of CO2 from flue gas stream. It was also found that the combination of 2 M acetic acid and water pretreatment improved the reactivity and capture capacity of the biomaterial for successive regeneration over four cycle’s usage. Unlike activated carbon, these biomaterials are considered stable for high-temperature adsorption through carbonation

Waste bone char-derived adsorbents: characteristics, adsorption mechanism and model approach.

The increase in meat consumption will result in a significant amount of bone being generated as solid waste and causing pollution to the environment. By pyrolysis or gasification, waste bones can be converted into bone char (BC), which can be used as an adsorbent for removing pollutants from wastewater and effluent gas. The purpose of this study is to critically appraise results from pertinent research and to collect and analyse data from studies on BC adsorbent applications from experimental, semi-empirical, theoretical and contextual viewpoints. Detailed descriptions of the theoretical adsorption mechanism, as well as possible interactions between pollutants and BC surface, were provided for the removal of pollutants. The study provides insights into the effect of synthesis conditions on BC's physicochemical properties and strategies for improving its adsorption capacity as well as future outlooks to guide research and support the development of green and cost-effective adsorbent alternatives to tackle water pollution. Additionally, this review discusses the application of BC to remove contaminants from water and soil, outlines strategies for regenerating pollutant-saturated BC, interprets the adsorption kinetics and isotherm models used in BC sorption studies, and highlights large-scale applications using packed-bed columns. Consequently, we proposed that when selecting the optimum isotherm model, experimental data should be used to substantiate the theory behind the predicted isotherm. Therefore, error functions combined with non-linear regression are the most effective method for obtaining and selecting optimal parameter values for adsorption kinetics and isotherm models

Food waste and circular economy:challenges and opportunities

The world’s population is expected to grow at an increasing rate, leading to increased food consumption and waste production. Even though food waste represents one of the most challenging economic and environmental issues of the 21st century, it also provides a vast array of valuable resources. To address the challenge, this study uses resource recovery from food waste to close the supply chain loop, which is the cornerstone of a circular economy. By applying the bibliometric review technique, trends and patterns in food waste and circular economy were studied. The analysis of frequent keywords in the field provided insights into further research directions. A Boolean search of the keywords in the Scopus database resulted in 288 articles, published between 2015 and 2021. Further screening of titles, keywords, and abstracts resulted in 155 journal articles. Bibliometric coupling, including authors’ co-citation data, co-occurrence, and the occurrence of keywords, was graphically mapped using VOSviewer software. From the analysis of the publications, eight broad themes emerged: (1) anaerobic digestion of food waste for circular economy creation; (2) food waste systems and life cycle assessments for circular economy; (3) bio-based circular economy approaches; (4) consumer behavior and attitudes toward circular economies; (5) food supply chains and food waste in a circular economy; (6) material flow analysis and sustainability; (7) challenges, policies, and practices to achieve circularity; and (8) circular economy and patterns of consumption. Based on the eight themes, we emphasize an urgent need to promote the collaboration of governments, the private sector, educational institutions, and researchers, who should combine efforts to promote, integrate and accelerate acceptance of circularity, which will potentially mitigate greenhouse emissions associated with food loss and waste. We also highlight an opportunity to encourage consumer acceptance of upcycled food in the food waste hierarchy. In addition, we deduce that there is a need to quantify food waste and emissions of greenhouse gases due to this waste along the food value chain; this is important as it is one pathway of examining the ‘food leaks’ along the food supply chain. This can then inform optimal strategies targeting specific areas of the food supply chain experiencing food leaks. Lastly, food wastage affects the entire globe; however, future studies and funding need to be channeled towards investigating the possibility of implementing circularity in developing countries.</p

A comparative study of fixed-bed and dispersed catalytic upgrading of heavy crude oil using-CAPRI

AbstractCAtalytic upgrading PRocess In-situ (CAPRI) incorporated with Toe-to-Heel Air Injection (THAI) for heavy oil and bitumen recovery and upgrading was studied for fixed-bed and dispersed catalysts. The extent of upgrading was evaluated in terms of API gravity, viscosity reduction, impurity removal, and true boiling point (TBP) distribution. The test was carried out using Co-Mo/Al2O3 at temperature of 425°C, pressure 20bar, and residence time of 10min. The dispersed catalyst was tested in a batch reactor. However, the residence time, catalyst-to-oil (CTO) ratios as well as the Reynolds numbers of both contacting patterns were kept the same to ensure dynamic similitude. It was found that the produced oil from dispersed ultrafine Co-Mo/Al2O3 catalyst (dp=2.6μm) exhibited superior light oil characteristics and quality than that produced with the fixed-bed of pelleted Co-Mo/Al2O3 (1.2mm diameter×2–5mm length). The API gravity of the feed oil was 13.8° and the produced oil showed an increase of 5.6° in the fixed bed and 8.7° with the dispersed catalyst. Unlike the fixed-bed of pelleted Co-Mo/Al2O3 which may suffer from diffusion limitations, rapid deactivation, and channelling effect, the ultrafine particles presented high surface area to volume ratio, reducing the chances of pore plugging, have more accessible reaction sites per unit mass, and lead to enhanced cracking of macromolecules. Moreover, the reduction of sulphur of 38.6% and (Ni+V) content of 85.2% in the produced oil show greater heteroatom removal compared to 29% (sulphur) and 45.6% (Ni+V) observed in the product from the fixed-bed

Hydrogenation and dehydrogenation of Tetralin and Naphthalene to explore heavy oil upgrading using NiMo/Al₂O₃ and CoMo/Al₂O₃ catalysts heated with steel balls via induction

This paper reports the hydrogenation and dehydrogenation of tetralin and naphthalene as model reactions that mimic polyaromatic compounds found in heavy oil. The focus is to explore complex heavy oil upgrading using NiMo/Al2O3 and CoMo/Al2O3 catalysts heated inductively with 3 mm steel balls. The application is to augment and create uniform temperature in the vicinity of the CAtalytic upgrading PRocess In-situ (CAPRI) combined with the Toe-to-Heel Air Injection (THAI) process. The effect of temperature in the range of 210&ndash;380 &deg;C and flowrate of 1&ndash;3 mL/min were studied at catalyst/steel balls 70% (v/v), pressure 18 bar, and gas flowrate 200 mL/min (H2 or N2). The fixed bed kinetics data were described with a first-order rate equation and an assumed plug flow model. It was found that Ni metal showed higher hydrogenation/dehydrogenation functionality than Co. As the reaction temperature increased from 210 to 300 &deg;C, naphthalene hydrogenation increased, while further temperature increases to 380 &deg;C caused a decrease. The apparent activation energy achieved for naphthalene hydrogenation was 16.3 kJ/mol. The rate of naphthalene hydrogenation was faster than tetralin with the rate constant in the ratio of 1:2.5 (tetralin/naphthalene). It was demonstrated that an inductively heated mixed catalytic bed had a smaller temperature gradient between the catalyst and the surrounding fluid than the conventional heated one. This favored endothermic tetralin dehydrogenation rather than exothermic naphthalene hydrogenation. It was also found that tetralin dehydrogenation produced six times more coke and caused more catalyst pore plugging than naphthalene hydrogenation. Hence, hydrogen addition enhanced the desorption of products from the catalyst surface and reduced coke formation

Value-added materials recovered from waste bone biomass: technologies and applications.

As the world population increases, the generation of waste bones will multiply exponentially, increasing landfill usage and posing health risks. This review aims to shed light on technologies for recovering valuable materials (e.g., alkaline earth material oxide such as CaO, hydroxyapatite, beta tri-calcium phosphate, phosphate and bone char) from waste bones, and discuss their potential applications as an adsorbent, catalyst and catalyst support, hydroxyapatite for tissue engineering, electrodes for energy storage, and phosphate source for soil remediation. Waste bone derived hydroxyapatite and bone char have found applications as a catalyst or catalyst support in organic synthesis, selective oxidation, biodiesel production, hydrocracking of heavy oil, selective hydrogenation and synthesis of bioactive compounds. With the help of this study, researchers can gather comprehensive data on studies regarding the recycling of waste bones, which will help them identify material recovery technologies and their applications in a single document. Furthermore, this work identifies areas for further research and development as well as areas for scaling-up, which will lead to reduced manufacturing costs and environmental impact. The idea behind this is to promote a sustainable environment and a circular economy concept in which waste bones are used as raw materials to produce new materials or for energy recovery