Trimethylphosphine (TMP) is demonstrated as a suitable 31 P MAS NMR probe molecule for determining accessibility, environment, and spatial distribution of oxidation-active oxidic metal species on solid catalysts quantitatively. It oxidizes to trimethylphosphine oxide (TMPO) at oxygen donor sites, which is demonstrated for oxides of copper, manganese, cobalt, and molybdenum. At loadings <2 wt % of Mo a direct quantitative correlation between TMPO quantity and accessible metal oxide content is observed. Exceeding 2 wt % results in a gradual agglomeration and thus decreases the amount of available oxidative sites, probed as a decay of the amount of TMPO formed. Additionally, the spatial distribution of oxides neighboring species could be inferred. The solid TMPO deposited near MoO x species was very sensitive to extra framework aluminum (EFAL) as well as Brønsted acid sites in close proximity, depending on Mo loading. Thus, the TMP method provides unprecedented insights into the surface chemistry of oxidative metal oxide catalysts.

We identify favorable parameters for the formation of aromatics from ethanol-based feeds over ZSM-5. An ethanol partial pressure of 0.3 bar, a reaction temperature of ∼700 K, a low weight hourly space velocity (WHSV), and a high Brønsted acid site density increase the content of aromatics, in the latter case, on the expense of lifetime. The aromatic fraction composition changes with the WHSV and n Si/n Al ratio. Water cofeed increases the content of aromatics in the C2:H2O stoichiometry of 1:0.5 (equals diethyl ether as feed) but decreases it if this is exceeded. Diethyl ether and ethylene lead to more aromatics than ethanol feed. The lifetime until deactivation increases in the order ethanol < diethyl ether < ethylene. This points at different reaction and/or deactivation mechanisms in converting the three feeds. Thus, a water-poor feed effectively improves the catalyst lifetime and productivity in the ethanol conversion to aromatics.

Organometallic complexes are frequently deposited on solid surfaces, but little is known about how the resulting complex−solid interactions alter their properties. Here, a series of complexes of the type Cu(dppf)(L x ) + (dppf = 1,1′-bis(diphenylphosphino)ferrocene, L x = monoand bidentate ligands) were synthesized, physisorbed, ion-exchanged, or covalently immobilized on solid surfaces and investigated by 31 P MAS NMR spectroscopy. Complexes adsorbed on silica interacted weakly and were stable, while adsorption on acidic γ-Al 2 O 3 resulted in slow complex decomposition. Ion exchange into mesoporous Na-[Al]SBA-15 resulted in magnetic inequivalence of 31 P nuclei verified by 31 P-31 P RFDR and 1 H-31 P FSLG HETCOR. DFT calculations verified that a MeCN ligand dissociates upon ion exchange. Covalent immobilization via organic linkers as well as ion exchange with bidentate ligands both lead to rigidly bound complexes that cause broad 31 P CSA tensors. We thus demonstrate how the interactions between complexes and functional surfaces determine and alter the stability of complexes. The applied Cu(dppf)(L x ) + complex family members are identified as suitable solid-state NMR probes for investigating the influence of support surfaces on deposited inorganic complexes.

Herein, desilication in increasingly harsh conditions was used to introduce mesopores into two different industrial ZSM‐5 catalysts (Si/Al ratio 11 or 29). For desilicated samples, increasing BET surface areas, mesopore volumes, and Si(OH) densities were noted. Brønsted acid site (BAS) densities increased upon desilication, as formerly inaccessible BAS in blocked pores became available, while the strength of the BAS was maintained upon desilication. Using KOH instead of NaOH as desilication agent can increase the mesopore volume generated per mass loss. The correlations between desilication strength and properties were largely determined by the parent Si/Al ratio. In general the introduced mesopores increased lifetimes in the ETA conversion, while additional Si(OH) groups introduced by desilication reduce the lifetime again. The lifetime is thus determined by a complex interplay of BAS density, improved reactant transport by introduced mesopores and Si(OH) density. There were no additional aromatics formed in desilicated samples during the conversion of ethanol and the samples were, in terms of aromatic yield, outperformed by a microporous parent. However, as result of longer lifetimes less ethanol was lost due to coke formation. It is concluded that desilication should be combined with other post‐modifications to increase aromatic production and lifetime.