respectively. It should be noted that the enthalpy of -35.1 kJ/ mol agrees with the previously reported value of -34.7 kJ mol-1,13 and the negative value indicates that the acetalization is an exothermic reaction. Given the suitable catalyst to 1,3-PDO ratio of 0.7 previously determined, the reactivity of the catalyst toward acetalization was compared with the commercial catalysts Dowex 50-WX4200 and Amberlite IR120 for the reactions carried out at 35 °C. The conversions, after reaction times of up to 120 min, are shown in Figure 7. At reaction times of 60 and 90 min, Dowex 50-WX4-200 and Amberlite IR120 hydrogen form were found to have higher reactivities compared with the synthesized carbon-based catalysts. Nevertheless, with the reaction time of 120 min, the reactivity of carbon-based catalyst was comparable to those of the commercial catalysts. The lower reactivity of the synthesized catalyst could be due to lower acid site, pore volume, and surface area as demonstrated in Table 1. Despite this, the lower cost of the carbon-based catalyst compared to the commercial catalysts demonstrates the potential application and suggests possible future development of the carbon-based catalyst for this application. 3.3. Evaluation of Catalyst Reusability. Other than reactivity, deactivation of the carbon-based catalyst was compared with those of commercial catalysts to evaluate the catalyst reusability. Here, acetalization of 1,3-PDO at 35 °C was carried out repeatedly with the reaction time of 120 min for each reaction cycle. As shown in Figure 8, in the second and third reaction cycles, the reactivity decreased for all catalyst. The synthesized carbon-based catalysts deactivated considerably compared to the