Synthesis of high hydroxyl value polyol from rubber seed oil by using Na2WO4/H3PO4/H2O2-based catalyst complex formed in aqueous phase

Abstract

Very high acid value rubber seed oil (RSO) and low acid value esterified rubber seed oil (RSOE) were used to synthesize high hydroxyl polyols in a one-pot two-temperature stage reaction. The Fourier transform infrared spectra and proton nuclear magnetic resonance spectra demonstrated the presence of hydroxyl groups in the polyols. By optimizing the influence of H2O2 content and technological conditions such as hydroxylation temperature, pre-reaction time, and hydroxylation time, a suitable technological process for polyolization was found for each oil. With the same pre-reaction time (20 min) and hydroxylation time (2 h), 100°C was the suitable temperature for RSOE polyolization and 110°C for RSO. Due to the very high acid value of RSO, the appropriate H2O2 content for its polyolization (DB (double bond)/H2O2 ratio of 1/1.75) needed to be larger than that for RSOE polyolization (DB/H2O2 ratio of 1/1.5). The catalytic selectivity in RSOE polyolization was very high (0.91), so the hydroxyl value of the RSOE polyol reached 500 mgKOH/g while it was only 393 mgKOH/g with RSO polyol.