Continuous H₂O₂ direct synthesis process: an analysis of the process conditions that make the difference

Abstract

A trickle bed reactor (TBR) was used to study different process parameters upon hydrogen peroxide direct synthesis. The catalysts used were commercial palladium on active carbon. The influence of pressure (1.75-25 barg), temperature (5-60°C), liquid flow rate (2-13.8 ml·min -1 ), gas flow rate (3.4-58.5 ml·min -1 ), catalyst amount (90-540 mg), Pd percentage on the support (5% wt., 10% wt. and 30% wt. Pd/C) as well as promoter concentrations (0.0005-0.001 m) were all varied as process parameters to better understand the behaviour of the system. By contrast, the gas phase molar composition of the feed (4:20:76 = H 2 :O 2 :CO 2 ) was kept constant. The strong influence between liquid flow rate, gas flow rate and catalyst amount were identified as the key parameters to tune the reaction, and related to the activity of the catalyst. In essence, these parameters must be carefully tuned to control the hydrogen consumption. The maximum productivity (289 μmol H 2 O 2 ·min -1 ) and yield (83.8%) were obtained when a diluted bed of 30% Pd/C was applied. The H 2 O 2 hydrogenation was studied in order to understand its role in the H 2 O 2 direct synthesis reaction network. The hydrogenation reaction mechanism and the role of NaBr were identified thanks to the experiment proposed in the present work. Consequently, understanding the whole reaction mechanism from the process conditions studied led to a deeper understanding of all of the phenomena involved in the H 2 O 2 direct synthesis.

Electrochemically Modeling a Nonelectrochemical System: Hydrogen Peroxide Direct Synthesis on Palladium Catalysts

“…On the basis of the LH mechanism, several DFT studies have explored the effects of coadsorbates ,− various facets, alloying effects, , and surface oxidation . Despite the theoretical advances in HPDS with DFT methods based on the LH mechanism, the studies showed the main reaction (H 2 O 2 production) to be kinetically unfavorable relative to the side reaction (H 2 O production), which is in contrast to experimental results reporting that H 2 O 2 production is kinetically more favorable than H 2 O production . Moreover, recent experimental findings suggested that the solvent and H + ion concentration play an important role in the HPDS reaction. − These experimental results are difficult to explain with the LH mechanism.…”

“…18 Despite the theoretical advances in HPDS with DFT methods based on the LH mechanism, the studies showed the main reaction (H 2 O 2 production) to be kinetically unfavorable relative to the side reaction (H 2 O production), which is in tion. 28 Moreover, recent experimental findings suggested that the solvent and H + ion concentration play an important role in the HPDS reaction. 29−31 These experimental results are difficult to explain with the LH mechanism.…”

A fuzzy collaborative intelligence approach for estimating future yield with DRAM as an example

“…Yield has been recognized as an essential factor to the competitiveness and sustainable development of a factory (Chen and Wang 2014). Elevating yield is also a critical task for green manufacturing, because a high yield minimizes scrap and rework, conserving materials, energy, time, and labor (Rusinko 2007;Zhang et al 2016;Huerta et al 2016). For these reasons, all factories have sought to enhance yield.…”

Manifesting Direction-Specific Complexation in [HFIP–H·H2O2]−: Exclusive Formation of a High-Lying Conformation

“…11,12 Additionally, the immiscibility of H 2 O 2 with nonpolar olefins in organic medium presents another major drawback. 13,14 Fluorinated alcohols are a class of extraordinary organic solvents with powerful dissolving ability while maintaining water-soluble properties. 15−19 Perfluorinated alcohols, particularly 1,1,1,3,3,3-hexafluoroisopropyl alcohol (HFIP) and 2,2,2-trifluoroethanol (TFE), were applied as solvents to catalytically activate H 2 O 2 in the absence of any metal oxides, permitting selective epoxidation of alkenes and Baeyer−Villiger oxidation of ketones.…”

“…Catalytic oxidation of olefins to produce epoxides commonly takes place in the presence of oxidants such as peroxomonosulfate, percarbonic acids, or hypochlorites, which inevitably produces large amounts of chemical waste byproducts and is thus not economically promising. Hydrogen peroxide (H 2 O 2 ), as an affordable and environmentally benign oxidant, provides an attractive option for alkene epoxidation, which, however, requires additional catalysts mostly associated with transition-metal oxides to be electrophilically activated. , Additionally, the immiscibility of H 2 O 2 with nonpolar olefins in organic medium presents another major drawback. , …”