## 3 Result and Discussion
### Catalyst Activity and Selectivity in Hydrodeoxygentation Reaction  
The characteristics of zeolite as a catalyst can affect the selectivity of the conversion of oxygenase to phenol and its derivatives. The surface morphology of the catalysts observed through SEM and EDX shows a homogeneous crystalline grain size and reduced impurity levels after the dealumination and impregnation of Ni. Such a catalyst surface allows the HDO reaction to run more optimally, without impurities that will interfere with the reaction. The highest surface area, total pore volume, and average pore are indicated by the Z7 catalyst, followed by Z5 and Ni-Z7 catalysts. A wider surface on the catalyst allows a greater area for the HDO reaction. A large total pore volume allows more frequent adsorption-desorption processes on the catalyst. Z5 catalyst with the highest surface area reached 132.44 m\({}^{2}\)/g and total pore volume reached 0.207 cc/g, resulting in a total phenol content high enough to reach 60.39%. Crystal size zeolite catalysts for acid activation and Ni-zeolite in this study are all included in the mesoporous size in the range of 13-41 nm. Mesoporous material is reported to have fast diffusion and is accessible for bulky molecules [37]. For HDO reactions of liquid smoke in this study, catalysts Z3, Z5, Ni-Z3, and Ni-Z5, which have larger crystalline sizes, have a higher total conversion of alkoxy compounds to phenols compared to Ni-Z7 catalysts, which have the smallest crystal sizes. The increased mesoporous improved the accesebility of acid sites and could also give great performance in many other acid-catalyzed reactions involving bulky molecules [38]. In a bifunctional catalyst, the metal site acts as hydrogenation and the Bronsted acid site on the zeolite has a role in the dehydration reaction. The center of the metal accelerates the rate of dehydration for phenols at the Bronsted acid site in zeolite, where on the other hand, the Bronsted acid site increases the HDO rate that is taking place in the bifunctional reaction [18]. The Bronsted acid site in zeolite binds with hydrogen and it easily releases the hydrogen to react with the hydrodeoxygented compounds [39]. The catalytic performance of Ni-Z-reducing oxygenase compounds is better than the Z catalyst. In the HDO reaction, the HDO process with the Ni-metal-impregnated zeolite catalyst in NZ is better at reducing alkoxy compounds in liquid smoke than nonimpregnated zeolite catalysts. In a bifunctional catalyst, the metal site acts as hydrogenation and the Bronsted acid site on zeolite has a role in the dehydration reaction. The center of the metal accelerates the rate of dehydration for phenols at the Bronsted acid site in zeolite, where on the other hand, Bronsted acid site increases the HDO rate that is taking place in the bifunctional reaction [18]. In the guaiacol conversion to catechol reaction using the bifunctional NZ catalyst, demethylation, or the direct release of CH\({}_{4}\) (methyl), occurs. H\({}_{2}\) gas binds with CH\({}_{3}\) to form CH\({}_{4}\), whereas other compounds bind with Ni metal. Then, H\({}^{+}\) from the Bronsted acid in zeolite is bonded by atom O from guaiacol that had lost CH\({}_{3}\) and catechol is formed [35]. The Ni-Z5 catalyst is considered to support HDO catalytic activity better than other catalysts, as seen from the decrease in alkoxy compounds that reached 11.49%. Judging from the properties of the catalyst, Ni-Z5 has the least amount of carbon, where the amount of deposited carbon can cover the surface of the catalyst so that it interferes with catalytic activity. In addition, this catalyst has a large crystal size. Overall, liquid smoke as the product of HDO with the Z7 catalyst experiences a decrease in phenol, alkoxy and other functional groups. This is suspected to be the deactivation of the catalyst due to the fouling occurring on the surface. [PERSON] et al. [40] reported that catechol--the same compound found in liquid smoke from HDO in the research--has more tendency to cause fouling than phenol.