1. Section 4 spends enormous effort proving that hierarchical mesopores/macropores are essential for alleviating diffusion limitations. Section 5 then discusses shaping these materials via extrusion or 3D printing. However, the paper completely omits quantitative data on how industrial shaping (with binders like bentonite, clays, or alumina—often added at 20–40 wt%) actively crushes, blocks, or fills these precisely engineered mesopores.
If the industrial shaping process destroys the mesoporosity that the first half of the review argues is critical, then the entire premise of translating lab-scale hierarchical zeolites to commercial pellets is invalid. The paper presents shaping as a mere “engineering step,” but it is actually a destructive process that often reverts the catalyst to a purely microporous state. Without addressing this, the review is scientifically misleading about industrial feasibility.
2. Section 6.2.2 claims that machine learning identified 469 novel OSDA structures with predicted stabilization energies “better than or comparable to the best-known templates” for zeolite Beta.
This is presented as a major breakthrough, yet the reference for this specific claim appears to be missing or incorrectly cited in the text (the placeholder citation is unclear). More critically, not a single one of these 469 computationally generated molecules has been experimentally synthesized or tested in a lab. In zeolite chemistry, computational binding energy does not guarantee hydrothermal synthesis viability; kinetics and competing phases almost always defeat purely thermodynamic predictions. By presenting speculative computational hits as validated advances, the paper crosses from rigorous review into speculative hype, compromising its scientific integrity.
3. The authors (affiliated with Saudi Aramco and Dow) heavily promote specific emerging technologies like BASF’s X3D 3D-printing platform and cite a large cluster of patents (references 10–16).
This reads as a promotional vehicle rather than an objective critique. The paper fails to cite the substantial body of literature showing that 3D-printed zeolite monoliths suffer from severe diffusion limitations through the printed walls themselves, and that the geometric advantages are often offset by poor intrinsic utilization. By uncritically championing these patented technologies while glossing over their high cost, poor scalability, and binder-induced dilution, the review loses its impartiality. A review should weigh evidence neutrally; this one pushes a corporate narrative.
4. The paper boasts a staggering increase in MTH catalyst lifetime from “~10 hours to ~83 hours” (an 8.3× improvement) for hierarchical ZSM-5 (Section 4.3.3.1).
These two numbers are pulled from different literature sources conducted under entirely different reaction conditions (different temperatures, different Weight Hourly Space Velocities, and different definitions of “deactivation”—e.g., 90% conversion vs. 95% conversion). In catalysis, lifetime is exponentially sensitive to WHSV and temperature. Comparing absolute hours from unrelated studies is scientifically invalid. By presenting this as a direct benefit of hierarchical structuring, the authors are engaging in misleading data presentation that severely overstates the real-world impact, undermining the credibility of their entire catalytic performance analysis.