Concept Design And Evaluation of Hydrogen Storage in Co2 to Formic Acid Synthesis

Khan Muhammad Uzair

2019-2023

Bachelor in Mechanical Engineering

ABSTRACT

One of the greatest challenges facing humankind is the deliverance of sustained energy supply over the time horizon. Hydrogen in its gaseous form can be used as a potential medium for energy storage. The picture gets disturbed when its storage and delivery is taken into question, this is in effect because H2 is lightest of all the elements [1]. Formic acid is attractive hydrogen containing and carrier compound, it has a volumetric capacity of 53 g/100ml. The study has been undertaken to analyze the effects of different thermodynamic states on conversion of carbon dioxide into FA. Ruthenium based homogenous catalyst is used for modeled process. Thermodynamic analysis is carried out as primary objective of the thesis using commercial software Aspen One (Aspen plus V8.8). Upper and lower values of thermodynamic variables are taken from various sources. The prescribed catalyst showed satisfactory results at equilibrium stage. It is further noted that the FA synthesis yield is favored at high reactor temperature (150°) and relatively low pressures. Results are obtained and relations are being approximated which give the exact ratios of selected thermodynamic states on hydrogenation of CO₂ during formic acid complete cycle, the description of roadblocks affronting clean and intermittent free resources, future for H₂ based energy resources and the dynamics of FA as one of the unique hydrogens storing and transporting medium. Laboratory tested Ruthenium based catalyst for FA synthesis process using H2 and CO2 as feed stock materials. It is observed over many scientific methods that the usage of homogeneous noble metals-based reagent is most suitable for large scale manufacturing of formic acid using the hydrogenation of carbon dioxide. The Gibbs energy minimization technique has revealed that the Gibbs energy for the reaction process for formic acid synthesis is positive. An addition of starting energy would be required for the activation stage of the process. The CO2 conversion has shown positive correlation with the rising temperature values in the range of 320°C and the range of 720°C with the constant pressure lines. It is further concluded that a positive correlation is found between the temperature values in the range of 320° C and 720°C at constant pressure values of 1, 3, 5 (MPa). From the design perspective the usage of multi stage compression greatly reduces the overall work input as well as increases the compression ratio for each compressor unit [2].

Key Words: Aspen plus; CO₂; H₂; Formic acid