## 1 Introduction  
Due to fossil fuels exhaustion, the growth of concern about global warming, and the increase in major air toxics, hydrogen has emerged as one of the best clean energy vectors [1]. H\({}_{2}\) can be produced from maintainable liquid fuels or phenols that consist of around 38 wt % [2] of the unwanted component of pyrolysis oil. However, this component can be transformed into H\({}_{2}\) rich gas, which makes phenol an ideal potential H\({}_{2}\) source. Based on previous research, there are two successive reactions that may take place in the steam reforming of phenol [3]. One of the reactions for H production from phenol is steam reforming of phenol (SRP), which can produce more H\({}_{2}\) yield based on stoichiometry in Equations (1) and (2):  
\[\mathrm{C}_{6}\mathrm{H}_{5}\mathrm{OH}+5\mathrm{H}_{2}\mathrm{O}\ \rightarrow\ 6 \mathrm{CO}+8\mathrm{H}_{2},\ \Delta\mathrm{H}^{o}=710.91\ \mathrm{kJ}/\mathrm{mol} \tag{1}\]  
\[\mathrm{CO}+\mathrm{H}_{2}\mathrm{O}\leftrightarrow\mathrm{CO}_{2}+\mathrm{H} _{2}\,\ \Delta\mathrm{H}^{o}=-41.15\ \mathrm{kJ}/\mathrm{mol} \tag{2}\]  
Ni-based catalysts with a high activity for the phenol steam reforming process have been investigated extensively in recent years [4; 5; 6] due to the ability to cleave C-C, O-H, and C-H bonds [7]. In addition, cobalt can assist with C-C bond cleaving at temperatures as low as 400 \({}^{\circ}\)C; this shows high production of H\({}_{2}\) and CO\({}_{2}\)[8] due to the highly favourable water gas shift reaction [9; 10; 11]. However, there are a few items that can be identified as the catalyst in the reforming of phenol: the conversion of phenol, and the yield of H\({}_{2}\), CO or CO\({}_{2}\). Many issues affect this performance, such as the steam to phenol (S/P) ratio, catalyst composition, flow rate of carrier gas, operating temperature, reactant feed rate and space time, preparation method, catalyst particle size, amount of catalyst, and ratio of active metals in multiple active metal catalyst use. Exothermic reactions, high phenol conversion, and the rate of gas production all occur at a high temperature. The same results were found in previous works regarding the temperature effect on phenol conversion. Some researchers have found that the conversion of phenol increased with the increasing of temperature [6; 12; 13; 14]. Based on the works of [PERSON] et al. [13] and [PERSON] et al. [15], the increase in catalyst activity is based on the increasing temperature. They have found that a complete phenol conversion occurs at high temperatures. There has been no research studying the amount of catalyst, the feed reactant flow, or the metal ratio in the steam reforming of phenol. However, some previous works did use other feeds like methanol, acetic acid, glycerol, and alcohol. Regarding previous works, increasing the space time [16; 17] or expanding the contact time by increasing the amount of the catalyst [18; 19] can result in an increase in the activity of the catalyst. However, the catalytic performance also depends on the kind of catalyst [17; 20; 21] and the technique of catalyst preparation [17]. DOE methods are more suitable than one-factor-at-a-time techniques because by studying multiple factors at the same time, a high efficiency can be obtained. These techniques have the following common benefits [22]: (1) more information per experiment than accidental methods; (2) a decrease in the number and fee of experiments; (3) making the calculation of the interaction amongst possible variables within the series studied, leading to better facts about the process; and (4) simplifying the description of the significant operation conditions for the scale-up process. Therefore, these techniques have been considered as powerful tools for process examination [23; 24; 25; 26; 27]. A numerical design of experiment (DOE) was applied in order to investigate the interaction amongst factors and the significance of factors on phenol conversion.