# Triggering hydrogenolysis of the lignin model compound benzyl phenyl ether using the intrinsic exothermicity of Pd-hydride formation

## TL;DR

This study shows that the heat from Pd-hydride formation can trigger the breakdown of a lignin model compound without external heating.

## Contribution

The work demonstrates that Pd-hydride exothermicity can initiate lignin model compound hydrogenolysis under ambient conditions.

## Key findings

- Pd-hydride formation generates heat flows of 58, 40, and 32 W g−1 on carbon, silica, and alumina supports.
- Higher heat flow correlates with increased BPE conversion and better Pd particle dispersion.
- X-ray absorption spectroscopy confirms Pd-hydride formation during the reaction.

## Abstract

When supported Pd catalysts are exposed to hydrogen, the heat released from the spontaneous and exothermic Pd-hydride formation creates a reaction environment that allows for melting and hydrogenolysis of benzyl phenyl ether (BPE) under nominally ambient conditions. The intrinsic exothermicity of this hydride formation acts as an initiating force for α-O-4 ether cleavage of the BPE dimer, without the need for external heat to be applied to the reaction system. Thermogravimetric analysis with differential scanning calorimetry shows heat flows of 58, 40, and 32 W g−1 for Pd supported on carbon, silica and alumina, respectively. BPE conversion increased with increasing heat flow, which correlated with a higher Pd particle dispersion and lower heat capacity of the support. X-ray absorption spectroscopy at the Pd-K edge confirms Pd-hydride formation. This work shows that the heat released by Pd-H formation can be used as an initiator for α-O-4 ether cleavage in a solid lignin model compound.

When Pd catalysts are exposed to H2, the heat released from the spontaneous, exothermic Pd-hydride formation creates a reaction environment that allows for melting and hydrogenolysis of benzyl phenyl ether under nominally ambient conditions.