Eurasian Journal of Chemical, Medicinal and Petroleum Research

Abstract This study explores the effects of temperature and pressure variations on catalyst degradation mechanisms—specifically catalyst crushing and catalyst cake formation—in a light naphtha isomerization unit. Operating conditions within the range of 200–280°C and 10–35 bar were simulated to evaluate mechanical and physical stress on the catalyst bed. Two performance indices were defined: the Catalyst Crushing Index (CCI) and Catalyst Cake Thickness (CCT). Results revealed that both CCI and CCT increase significantly with rising temperature and pressure, with pressure having a more pronounced impact. Elevated pressure intensified catalyst compaction, while temperature contributed to structural weakening and sintering. The analysis showed that high-pressure environments above 25 bar and temperatures exceeding 260°C led to accelerated crushing and cake buildup, contributing to pressure drop, pore blockage, and reduced hydrogen diffusion. These degradation mechanisms ultimately reduce catalytic activity and operational efficiency. The findings suggest that maintaining optimal reactor conditions and incorporating real-time monitoring systems are essential for preventing early catalyst failure. This research provides a predictive framework for improving catalyst performance and life cycle in isomerization processes and can support operational decision-making in refinery settings.

Abstract In this article, while reviewing the "EPC" contracts and the different stages of risk management according to the "PMBOK" standard, a general proposed model for this type of contract is presented, in which the necessity of planning and managing risk in the stages before winning the tender and after winning and signing the contract has been examined and considered. In recent years, the construction market has moved towards contracts in which the final amount and the time of completion of the work are guaranteed. Risk management knowledge, as a subset of project management knowledge, has gradually become a source of influence with such developments. The "PMBOK" standard has divided the risk management process into 6 stages: risk planning, risk identification, qualitative risk analysis, quantitative risk analysis, risk response and risk control. The proposed model in this research is that the contractor must implement stages 1 to 4 of risk management before bidding and after signing the contract, perform the 6 mentioned stages. In this model, the results of the pre-bid risk management review can be used as input to the post-contract phase. The six risk management phases operate like a cycle and are similar to a trial and error method. Initially, the work phases begin with limited parameters. As the project progresses and more details of the work are identified, the impact of risks on more activities must be considered and more risks become apparent, so risk management needs to plan, identify, analyze, respond to, and control new risks over a specific period of time. Methods were also proposed and reviewed for the risk planning and risk identification phases, so that EPC contractors can more easily review and manage risks in these types of contracts.