Nejat Rahmanian

This study evaluates the technical, environmental, and economic performance of an integrated CO₂ capture and methanol synthesis process enhanced through systematic thermal integration. The system was modelled in Aspen Plus™ using flue gas containing 14.88 mol% CO₂ as the feed stream. Approximately 91 mol% of the CO₂ is captured, corresponding to 17,210 kg·h⁻¹ of CO₂ compressed to 50 bar and utilized for methanol synthesis. Pinch analysis was applied to identify heat recovery opportunities between the CO₂ capture and methanol synthesis units, enabling the development of an optimized heat exchanger network that maximizes internal heat recovery and minimizes external utility demand. Thermal integration significantly improves the energy efficiency of the system. The proposed retrofit enables the recovery of approximately 4.01 × 10⁷ kJ·h⁻¹ of heat, which can be used to generate medium-pressure steam and offset nearly 39% of the CO₂ capture solvent regeneration reboiler duty. Overall, external steam consumption is reduced by about 40% compared with the base configuration. Additional energy savings are achieved through the integration of a turbo-expander with the hydrogen compression system, which recovers approximately 757 kW of mechanical power and supplies around 12.7% of the compressor energy demand.The environmental assessment shows that the reduction in external energy consumption leads to improvements across several life-cycle impact categories, including greenhouse gas emissions, fossil resource depletion, photochemical oxidation potential, and marine ecotoxicity. However, hydrogen production and electricity supply remain the dominant contributors to the system’s environmental footprint, indicating that the sustainability of CO₂-derived methanol strongly depends on the availability of low-carbon hydrogen and renewable electricity. From an economic standpoint, the reduction in utility consumption and improved heat recovery decreases operational energy costs and enhances overall process efficiency. Thermal integration also improves equipment utilization within the heat exchanger network and utility systems, which reduced capital requirements for auxiliary utilities. Overall, integrating CO₂ capture with methanol synthesis through optimized thermal integration can significantly enhance process efficiency while improving environmental and economic performance. The results highlight the importance of system-level energy integration and process optimization for advancing sustainable carbon capture and utilization pathways and supporting the development of low-carbon methanol production technologies.

Solid urea is the largest nitrogen fertilizer product, produced in two forms: granules and prills. Although the chemical properties of both prills and granules remain similar, their differing physical and mechanical properties distinguish them, making them suitable for different applications, either as fertilizers or raw materials for the chemical industry. This research aims to understand the differences between prilled and granulated urea by comparing their physical and thermal properties. The characterizations were conducted using thermal gravimetric analysis, differential scanning calorimety, Karl-Fischer titration, Scanning Electron Microscopy, High-Performance Liquid Chromatography, sieve analysis, strength measurements, and pycnometer. Karl Fischer titration revealed that granules contain more moisture (0.48%) compared to prills (0.34%). The moisture content of a fertilizer during storage and handling affects its overall quality. HPLC analysis on biuret content showed that the prilled samples contained higher biuret content. The results of the sieve analysis technique used to determine the size distribution indicated that granules had a larger mean diameter of 2.81 mm compared to prills, which had a mean diameter of 1.64 mm. SEM images revealed clear differences in terms of shape and structure between the prills and granules. The outer surface of the prills was smoother and glass-like, while the granules appeared rougher. Interestingly, on the inside, the granules had a denser and more solid middle layer. In contrast, the prills exhibited cracks throughout their inner structure.

Carbon dioxide (CO ₂ ) storage serves as a greenhouse gas mitigation strategy employed by numerous nations. This study aims to explore the feasibility of CO ₂ storage in the Rio del Rey Basin, Gulf of Guinea region. We employ a compositional flow model, which has been validated using data from a Subsurface interpretation project in Cameroon.This work is aimed at conducting compositional numerical simulations to investigate the impact of geochemistry on CO ₂ aquifer storage. A conceptual development CO ₂ storage study has been considered for a deep aquifer reservoir formation Miocene Rio del Rey Basin, Cameroon Gulf of Guinea. The reservoir formations in this basin are set to have very good petrophysical and geological properties for it to be considered as a storage system.The aquifer formation contains various amounts of minerals which in turn would alter the injection of CO ₂ as the chemical and geological properties of the storage system change. Some of the chemicals would alter the CO ₂ fluid and rock properties and consequently the reservoir injection and storage rates and quantities of injected and stored CO ₂ due to minerals precipitation and vaporization phenomena within the storage system. This presents a major concern as the impact of geochemistry on CO ₂ injection and storage is not well understood to date which means that the development and operational strategies and costs of such a project are not fully understood and present significant deployment risk and uncertainties.The simulation results show that aquifer geochemistry strongly affects CO ₂ brine water storage efficiency at different scales.

Oil reservoir formation damage is a significant issue in secondary and tertiary oil recovery operations. Enhanced oil recovery (EOR) approaches can address these issues while increasing production rates and resource recovery. However, challenges include chemical degradation, high chemical volumes, and high costs. Nanotechnologies can improve oil recovery by improving subsurface porous media and pore fluids, separating fluid phases, and introducing influencing coatings. Cobalt oxide-based materials have been extensively evaluated for their amphiphilic properties, thermal stability, and high reactivity, which can modify physicochemical properties and improve crude oil recovery. CoO nanoparticles were characterized using various techniques, including Fourier Transform Infrared Spectroscopy (FTIR), Raman spectroscopy, X-ray photoelectronic spectrometry, and Field Emission Scanning Electron Microscope (FSEM). Results showed that CoO nanofluid positively affects reservoir minerals with electromagnetic fields and improves oil recovery. It also improves thermal stability, promotes stable emulsion formation, decreases the interfacial tension (IFT) up to 15% for the light-crude-oil/water system at concentrations of 0.5 wt% nanofluid, and can improve thermal stability with respect to CoO in a wide range of temperatures, favouring the formation of stable emulsions.

Bioenergy stands as the primary contributor within the realm of global renewables, offering energy security to a multitude of individuals while also fostering growth in rural areas. The emergence of fuel pellets derived from diverse feedstocks has brought forth both prospects and obstacles for current technologies. This article delivers an up-to-date examination of the production and application of fuel pellets sourced from biomass. The upcoming discourse will explore the various aspects, both positive and negative, of the production and utilization of fuel pellets obtained from biomass, with a specific focus on the circumstances in the United Kingdom (UK). Through acquiring a thorough understanding of the manufacturing procedures of fuel pellets, coupled with a detailed examination of their benefits and drawbacks, the feasibility of utilizing biomass can be greatly improved, consequently leading to a significant contribution to the progression of a sustainable bioenergy framework.

In recent years, there has been a growing concern surrounding hydrogen energy and polymer electrolyte membrane (PEM) fuel cells. However, the advancement of fuel cell commercial development has been hindered by the limitations in constructing hydrogen refueling infrastructure, as well as hydrogen storage and transportation. This review provides a comprehensive analysis and comparison of various aspects, ranging from resources to end-using of hydrogen. The analysis focuses on the examination of the benefits associated with the application of surplus hydrogen of industrial sectors and the hydrogen produced by steam reforming gas in PEM fuel cell systems. The utilization of industrial wasted hydrogen presents a notable potential for a substantial decrease in the overall cost of hydrogen. Additionally, it is suggested that the employment of onboard hydrogen generation through steam methanol reforming can effectively address the challenges associated with the efficient storage and transportation of gaseous hydrogen. The introduction typically encompasses a discussion of the impacts arising from the presence of impurities in the reformate gas. Following the reformate gas becomes suitable for utilization in PEM fuel cells. Ultimately, recommendations are put forth for future investigations.