Our results demonstrated the two pathways of polyolefin conversion on the bifunctional Ru/TiO2-A-SG: hydrocracking and hydrogenolysis. Compared to hydrogenolysis, hydrocracking has several advantages. First, it produces minimal low-valued C1-3 products (Figure ). C-C cleavage in hydrocracking is mainly achieved through two types of β-scissions: type-A, which starts and ends both with a 3 C + , and type-B, which starts or ends with one 2 C + (Scheme 3). C1-2 are absent because the 1 C + intermediates involved in their formation are too unstable. 10 C3 yield is low because only type-B β-scissions at the chain ends can produce C3 (Scheme 3), which are much slower than type-A β-scissions. Besides, at the chain ends of virgin PP, primary βscissions always start with 3 C + , and thus there are no type-B1 β-scissions (Scheme 3). In contrast, primary C-C bond cleavage in hydrogenolysis does not discriminate against C1-3, and sequential C-C cleavage, if the desorption is slow, favors CH4 formation. Second, hydrocracking is more suitable for low-PH2 operation. When PH2 decreases from 30 to 5 bar, the PP conversion drops much less significantly on the bifunctional Ru/TiO2-A-SG (37% drop in Figure ) than on monofunctional Ru catalysts (70%, 80%, and 75% on 0.125%, 2% Ru/CeO2, and 5% Ru/C, respectively), and the former converts PP at least 7-fold faster at 5 bar. Third, hydrocracking is accompanied by isomerization, producing more branched alkanes from LDPE (Figure ) and likely aromatics (implied by the yellow color of products). Fourth, hydrogenolysis requires noble metals (Ru, Rh, or Pt with polyolefin substrates), while the non-noble metal Ni can catalyze hydrocracking even more efficiently than Ru (Figure ). Despite the superior efficiency and selectivity with PP, hydrocracking on Ni/TiO2-A-SG is not as effective as hydrogenolysis on Ru/TiO2-A-SG with less branched substrates (Table ), as the virgin structure with minimal 3 C requires extensive isomerization before β-scissions, and has less steric hindrance for hydrogenolysis. Thus, hydrogenolysis might be more suited for the upcycling of PE, particularly HDPE. Another undesired feature of PP hydrocracking on M/TiO2-A-SG is the strong tendency to produce C4-6 (Figure , observed at low PP conversion as well, Figure , C6 yield underestimated due to the fast evaporation). The high C4-6 yields on nonmicroporous catalysts are signs of significant secondary cracking, i.e., consecutive β-scissions before desorption, which will stop when the substrate does not have 7 C atoms (Scheme 3). This usually occurs because the dehydrogenation ability of the catalyst is too low to establish the alkane/alkene equilibrium, leading to low free alkene concentration that cannot displace products from BAS. Replacing Ni with Pt, which has better dehydrogenation ability, enhances the rate (Figure ), confirming that on Ni/TiO2-A-SG, dehydrogenation is the slow step. This also increases chances for type-B β-scissions and thus C3 formation. Type-A β-scissions require three branches in the α, α, γ-configuration (Scheme 3), which is absent in virgin PP/LDPE.