## 1 Introduction
[36] investigated the synthesis of a hybrid material of Pd nanoparticles encapsulated within carbon nanotubes (CNTs) (Pd-CNTs-in). The results show that the prepared Pd-CNTs-in catalyst exhibits particularly high formic acid decomposition activity and durability at room temperature. The TOF value was found to be 1135 h\({}^{-1}\) in the first 10 min, and there was no significant decrease in the continuous three-fold recovery study. The conclusion reached is that this work can provide a promising strategy for manufacturing cost-effective and highly active Pd-based catalysts for the dehydrogenation of formic acid. The investigation of formic acid decomposition in batch reactors is often limited by their ability to generate a continuous stream of H\({}_{2}\) for fuel cell applications. Moreover, these reactors do not permit a detailed study of the catalyst lifetime to give an indication of its long-term performance. Therefore, the study of formic acid decomposition in continuous-flow reactors is essential to the comprehensive understanding of this reaction. The decomposition of formic acid has been explored using homogeneous and heterogeneous catalysts in continuous stirred tank reactors (CSTR) [37; 38; 39]. [PERSON] et al. [40] investigated the production of hydrogen via the low-temperature (less than 110 \({}^{\circ}\)C), additive-free decomposition of formic acid over a heterogeneous Pd/C catalyst. The results show that, during continuous-flow operation, pore contamination and poisoning caused by formate ions lead to catalyst deactivation. Although these factors cause extensive deactivation in the plug-flow mode, by operating in a continuous stirred tank reactor to reduce the steady-state formic acid concentration, encouraging results can be obtained. Therefore, under mild conditions and without stoichiometric additives, the system can operate continuously for more than 2500 cycles without loss of activity. The decomposition of formic acid has often been investigated on an experimental basis. The utilisation of software for conducting detailed numerical studies can facilitate an understanding of parameter optimisation for the decomposition of formic acid reaction. Furthermore, theoretical studies are a valuable tool to assess the validity of the experimental findings [41; 42]. [PERSON] and [PERSON] et al. [43] investigated the liquid-phase decomposition of formic acid using a Pd/C catalyst in a packed bed microreactor. A comprehensive heterogeneous computational fluid dynamic (CFD) model was developed to validate the experimental data. The results showed that the CFD model demonstrated very good validation with the experimental work. Furthermore, the novel model could successfully depict the deactivation of the Pd/C catalyst based on the poisoning species CO. The model developed can be used to effectively predict the decomposition of formic acid in microreactors for potential fuel cell applications. The process-simulation modelling of formic acid decomposition has not been implemented for the current reaction system, which enhances the uniqueness of the current work. Process-simulation or flowsheet modelling can offer a solid foundation based on mass and energy balances, mass and heat transfer, reaction-system modelling, and phase equilibria to simulate the decomposition of formic acid. We utilised the capabilities of Aspen Plus to develop a simple innovative reaction system by integrating the phase-equilibrium exercises. It has been observed that both CFD and process-simulation modelling have the ability to predict different reactions with similar results [44]. The production of H\({}_{2}\) from the decomposition of formic acid has been investigated using a 2%Pd\({}_{6}\)Zn\({}_{4}\) catalyst in a batch reactor. A comprehensive process-simulation model has been developed based on the batch stirred reactor to validate the experimental findings. Further studies are performed to assess the characterisation and activity of the catalyst.