The hydrodemethylation (HDM) of toluene to benzene is an industrial process performed at elevated temperatures (≈500 °C and higher). Here, it was reported that heating graphite‐supported potassium hydride (KH/C) with toluene under H₂ atmosphere provided benzene already at 125–250 °C. Depending on the H₂ pressure, the reaction was either substoichiometric ( ≤11 bar) or catalytic ( ≥50 bar) with respect to KH, indicating that KH may serve as a radical chain initiator. At 250 °C, the selectivity to benzene was 98 and 63 % when using 6 and 80 bar of H₂, respectively, owing to the competing formation of cyclohexane and methylcyclohexane at high H₂ pressure. The used KH/C material was amenable to recycling without a notable loss in the yield of benzene.

Marvelous natures of alkali and alkaline earth metal hydrides in catalyzing chemical transformations are being discovered. However, the synthesis of (sub)nanostructured metal hydrides, critically important to enhance their catalytic performances, is yet a very challenging task. Herein, we develop a highly reactive heterogeneous catalyst comprising atomically dispersed barium hydrides on MgO support with an ultrahigh barium loading of up to 20 wt% via a convenient preparation method involving liquid-ammonia impregnation followed by hydrogenation. The surface barium hydride species not only exhibits extraordinary reactivity toward H₂ activation at room temperature, but also enables the highly efficient hydrogen isotope exchange (HIE) of both sp³ C–H and sp² C–H bonds in nonactivated alkylarenes using D₂ as the deuterium source under mild conditions. The deuteration rate at benzylic site is two orders of magnitude higher than that of bulk BaH₂. This study offers an alternative synthetic route for the manufacture of deuterium-labeled compounds using a heterogenous transition metal-free hydride catalyst beyond the widely studied molecular metal complexe catalysts.

The utilisation of fossil fuels has resulted in the continuous increase in anthropogenic carbon dioxide (CO₂) emissions and has led to significant environmental impacts. To this end, the catalytic hydrogenation of captured CO₂ into value-added C1 chemicals has attracted great attention. In this case, significant research efforts have been directed towards the development of heterogeneous catalysts. Owing to the unique properties and functionalities of hydridic hydrogen (H⁻), metal hydrides have shown great promise in hydrogen-involved catalytic processes. This is attributed to their enhanced hydrogen (H₂) absorption-desorption reversibility and newly developed active sites. Nevertheless, their application in the activation and hydrogenation of CO₂ has been overlooked. In this review paper, we provide an overview of recent advances in catalytic CO₂ hydrogenation using metal hydride-based materials. Firstly, the reaction mechanisms of CO₂ hydrogenation toward different C1 products (CO, CH₄, CH₃OH and HCOOH) are introduced to better understand their application trend. Thereafter, we highlight the challenges of developing robust hydride catalysts with different components and structures that enable tuning of their catalytic activity and selectivity. A brief introduction of the CO₂ hydrogenation over typical homogeneous metal hydrides complexes is also presented. Lastly, conclusion, future outlook and perspectives are discussed.