Gas-phase epoxidation of propylene over nanostructured iron-containing catalysts

Novelty without nobility: Outstanding Ni/Ti-SiO2 catalysts for propylene epoxidation

“…However, some problems are associated to these commercial processes: for example the use of dangerous and highly oxidizing reagents, such as Cl 2 or organic peroxides (R-OOH) and the generation of by-products which are difficult of separate. [2,3] One alternative to overcome these shortcomings is to produce PO by the oxidation of propylene via heterogeneous catalysis, since this methodology can avoid the use of Cl 2 or organic peroxides enabling the use of other more sustainable and environmentally friendly reagents like H 2 /O 2 or O 2 .…”

Gas-phase epoxidation of propylene over iron-containing catalysts: the effect of iron incorporation in the support matrix

“…On the other hand, with the increase of the calcination temperature, it is possible to incorporate higher amounts of iron into the silica matrix without losing the epoxidation performance. 9 Here we demonstrate that the presence of an excess chloride anions or strongly chelating ligands in the iron precursors promotes the formation of iron sites exhibiting high epoxidation activity. Simple iron salts, such as nitrate, chloride, and formate, as precursors for silica-supported catalysts result in low PO yields, moreover for such iron precursors the increase of iron contents in the catalyst above 0.1% results in a steep decrease in selectivity (Table 1).…”

“…The direct gas-phase epoxidation of propylene to PO has been studied in recent years as an alternative route to industrial processes. Different oxidizing agents, including molecular oxygen 8 and nitrous oxide 9,10 as well as H 2 -O 2 mixture 11,12 have been tested. Gold nanoparticles on TiO 2 were reported to catalyze propylene epoxidation using H 2 -O 2 mixture with very high PO selectivity (>95%).…”

“…In the presence of a calcium promoter, very high selectivity (96%) to PO was achieved. 9 In the present work the interactions between the catalyst support, iron and promoters are investigated. The separate effects of the cation and anion of the promoter are discussed in terms of the catalyst's lifetime and selectivity toward PO.…”

Gas-Phase Selective Oxidation of Butenes in the C4 Fraction by Nitrous Oxide

“…Nitrous oxide (N 2 O) has also attracted special attention as a promising selective oxidant for several potential applications such as the catalytic hydroxylation of benzene and its derivatives − or epoxidation of olefins. − It is important to note that N 2 O is produced in large amounts as a waste byproduct in a number of chemical processes. Since nitrous oxide is a long-lived greenhouse gas, ,, the reduction of its emissions remains one of the most urgent problems.…”