Low-carbon ketenes (LCK, Carbon number less than or equal to 5) play an important role in ketene family. In the present work, LCK production of two feasibly industrial processes, pyrolysis of acids and anhydrides, was explored by both theoretical and experimental ways. Firstly, computational chemistry was used to compare the two different methods by calculating the energy barrier heights and kinetic parameters of unimolecular pyrolysis of acids including dehydration and decarboxylation reactions and anhydrides including the formation of acids and ketenes. The results show that temperature of acids pyrolysis is far higher than that of anhydrides and ketenes selectivity of acids pyrolysis is 13% lower than that of anhydride at least. Then, experiments of isobutyric anhydride (IBAN) and isobutyric acid (IBA) pyrolysis were carried out to verify the reliability of computational chemistry results. Kinetic parameters of IBAN pyrolysis( k1=1012.35×e-160.38/RT s-1 for main reaction, k2=106.24×e-54.91/RT s-1M-1 for reverse reaction of main reaction, k3=106.86×e-72.43/RT s-1M-1 for CO2 and CO formation and k4=107.16×e-76.78/RT s-1M-1 for hydrocarbons formation) were obtained from experimental data. Finally, due to the lack of kinetic data of anhydrides pyrolysis and the little discrepancy of activation energy of main reaction between computational results, 160.38kJ mol-1, and experimental results, 160.84kJ mol-1, activation energy models of low carbon anhydrides pyrolysis were obtained by group additivity method developed by Marin and coworkers. Comparison between CBS-QB3 ab initio-calculated values and GA-calculated values shows that the activation energies generally agree within 4kJ mol-1.
