Carbon–carbon bond cleavage reactions, adapted to deconstruct aliphatic hydrocarbon polymers and recover the intrinsic energy and carbon value in plastic waste, have typically been catalysed by metal nanoparticles or air-sensitive organometallics. Metal oxides that serve as supports for these catalysts are typically considered to be inert. Here we show that Earth-abundant, non-reducible zirconia catalyses the hydrogenolysis of polyolefins with activity rivalling that of precious metal nanoparticles. To harness this unusual reactivity, our catalytic architecture localizes ultrasmall amorphous zirconia nanoparticles between two fused platelets of mesoporous silica. Macromolecules translocate from bulk through radial mesopores to the highly active zirconia particles, where the chains undergo selective hydrogenolytic cleavage into a narrow, C18-centred distribution. Calculations indicated that C–H bond heterolysis across a Zr–O bond of a Zr(O)2 adatom model for unsaturated surface sites gives a zirconium hydrocarbyl, which cleaves a C–C bond via β-alkyl elimination.

We have discovered a heterogeneous catalyst that aligns the proton magnetic moments in liquid water, methanol, and ethanol molecules by using parahydrogen. In this SWAMP (surface waters are magnetized by parahydrogen) effect, hyperpolarization of the solvent protons is induced simply by the bubbling of parahydrogen gas through a suspension of the intermetallic nanoparticle catalyst in the neat liquid. The conversion of singlet spin order into magnetization is mediated by surface interactions and intermolecular spin couplings. The SWAMP effect has promising applications ranging from low-field MRI to drug discovery.

Side‐arm hydrogenation (SAH) by homogeneous catalysis has extended the reach of the parahydrogen enhanced NMR technique to key metabolites such as pyruvate. However, homogeneous hydrogenation requires rapid separation of the dissolved catalyst and purification of the hyperpolarised species with a purity sufficient for safe in‐vivo use. An alternate approach is to employ heterogeneous hydrogenation in a continuous‐flow reactor, where separation from the solid catalysts is straightforward. Using a TiO2‐nanorod supported Rh catalyst, we demonstrate continuous‐flow parahydrogen enhanced NMR by heterogeneous hydrogenation of a model SAH precursor, propargyl acetate, at a flow rate of 1.5 mL/min. Parahydrogen gas was introduced into the flowing solution phase using a novel tube‐in‐tube membrane dissolution device. Without much optimization, proton NMR signal enhancements of up to 297 (relative to the thermal equilibrium signals) at 9.4 Tesla were shown to be feasible on allyl‐acetate at a continuous total yield of 33 %. The results are compared to those obtained with the standard batch‐mode technique of parahydrogen bubbling through a suspension of the same catalyst.

Intermetallic PtSn nanoparticles leads to pairwise-hydrogenation of alkynes to the corresponding cis-alkenes, satisfying both high stereoselectivity and high chemoselectivity.