Chemometric Assessment of Structure–Operation–Performance Relationships in Heterogeneous Biodiesel Catalysis

A literature-derived chemometric assessment was conducted to examine how catalyst structural characteristics and reaction operating conditions jointly organize the reported performance of heterogeneous biodiesel catalysts. A curated database contained 218 heterogeneous observations, of which 133 had complete operating variables, and 30 from 19 source studies contained the full structure–operation–performance dataset. Principal component analysis (PCA), hierarchical cluster analysis (HCA), hierarchical regression, and partial least-squares (PLS) validation were applied. PCA retained four components explaining 85.69% of the standardized variance, with reaction time and catalyst loading dominating the first component, while specific surface area (SBET) and pore volume contributed strongly to the second. HCA identified three exploratory multivariate profiles, although their exact partition showed sensitivity to selected source studies. In the 133-observation operation-only dataset, temperature and alcohol-to-oil ratio were positively associated with reported yield, whereas catalyst loading showed a negative association. For the 30 complete cases, adding structural descriptors increased explained variance from 7.44% to 48.63%. However, study-clustered inference weakened the significance of SBET, while PLS showed negative study-level predictive performance. The findings support multivariate structure–operation analysis but not transferable predictive catalyst selection or causal ranking.