_Applied_  
_sciences_  
_Nvel Polymer-Silica Composite-Based Bifunctional Catalysts for Hydrodeoxygenation of_  
_4-(2-Furyl)-3-Buten-2-One as Model Substance for_  
_Furfural-Acetone Aldol Condensation Products_  
**[PERSON] 1,*\(\copyright\), [PERSON] 2, [PERSON] 1\(\copyright\) and [PERSON] 3\(\copyright\)**  
Footnote 1: [[https://github.com/journals/michael-goepel/](https://github.com/journals/michael-goepel/)]([https://github.com/journals/michael-goepel/](https://github.com/journals/michael-goepel/))  
to obtain longer carbon chain organic molecules is based on the acid- [8; 9; 10] or base-catalyzed [11] aldol condensation of furfural with acetone and subsequent dehydration to 4-(2-furyl)-3-butene-2-one (FAc). The acetone for this reaction can also be obtained from bio-based resources via fermentation [12] or ketonization [13]. A further hydrodeoxygenation (HDO) of FAc is of key interest for the production of fuel additives and value-added chemicals and has been investigated in recent studies [10; 14; 15]. The reaction network for the HDO of FAc (requiring both acid and redox catalyst functionalities) is very complex, and the reaction may yield a broad variety of different products apart from the fully deoxygenated \(n\)-octane. For example, 1-octanol was identified as a valuable intermediate for the HDO of FAc [16]. While 1-octanol can be produced from FAc in biphasic aqueous reaction mixtures making use of its immiscibility with water [17], another approach to simply engineer the product composition of the FAc, HDO using a tailored catalyst is desirable. For this, a bifunctional catalyst whose acid and redox properties can be individually tuned would be of great interest. In this context, polymer-silica composite (PSC) catalysts offer great potential as an acid component of tailorable bifunctional catalysts. They have been first synthesized by [PERSON] et al. [18] at DuPont by embedding Nafion(r) type polymers into silica matrices by coprecipitation. In this work, [PERSON] et al. furthermore showed that the acid site density of these PSC-catalysts could simply be tuned by polymer content. In addition to that, they attributed an improved performance of the PSC catalysts over conventional Nafion(r)-based ion-exchange resin solid acid catalysts (i.e., Amberlyst-15 and NR50, which possess higher acid capacities) to the higher dispersion of the polymer species in the PSC catalysts. Despite their obvious potential as solid acid catalyst, and their application as (reference) catalyst in numerous studies [19; 20; 21; 22; 23], there are only a few studies published further investigating the PSC catalysts themselves. [PERSON] et al. found that the silica precursor used for the PSC catalyst synthesis might affect the catalytic performance [24]. Furthermore, the influence of polymer content on textural properties and catalytic performance in different acylation reactions was investigated by [PERSON] et al. [25; 26]. Concerning PSC-based bifunctional catalysts, only two studies could be found in the literature. In these investigations, Pt and Pd were added to the commercial SAC-13 catalyst via impregnation and the catalysts were used in the direct hydroxylation of benzene [27; 28]. When comparing these PSC-based bifunctional catalysts to conventional ion-exchange resins (Amberlyst-15) [28] and with other Pt- and Pd-modified acid catalysts (such as BEA, FER, MOR, and MFI zeolites), the PSC-based bifunctional catalyst showed a fivefold higher formation rate of phenol than all the other catalysts investigated in both studies. However, in these works, the amount of polymer (given by the loading of the commercial catalyst) and metal content was not varied and no content-dependent investigations were carried out. It is therefore the aim of this study to investigate the potential of metal-loaded PSC as tailorable catalysts in the HDO of FAc. For this purpose, PSC-based catalysts with varying polymer contents (0-26 wt.%) were synthesized and loaded with different amounts (0.5-2 wt.%) of noble metals (Pt, Pd, Ru).