DECHEMA

About: DECHEMA is a nonprofit organization based out in Frankfurt am Main, Germany. It is known for research contribution in the topics: Corrosion & Oxide. The organization has 756 authors who have published 1307 publications receiving 25693 citations.

An aqueous–organic two-phase bioprocess for efficient production of the natural aroma chemicals 2-phenylethanol and 2-phenylethylacetate with yeast

Abstract: The natural aroma chemicals 2-phenylethanol (2-PE) and 2-phenylethylacetate (2-PEAc) are of high industrial relevance and can be produced from L-phenylalanine in a yeast-based process with growth-associated product formation. Due to product inhibition, in situ product removal is mandatory to obtain economically interesting concentrations. A fed-batch approach using polypropylene glycol 1200 as in situ extractant and the precursor in a saturated concentration led to the highest 2-PE productivity reported for a bioprocess so far. With Kluyveromyces marxianus CBS 600, 26.5 g/l 2-PE and 6.1 g/l 2-PEAc in the organic phase were obtained, corresponding to space-time yields of 0.33 and 0.08 g/l h, respectively.

Chemo-mechanical effects of flow on corrosion

Abstract: Basic processes, parameters, and mechanisms are discussed with special reference to hydrodynamics, mechanical actions of one- and two-phase flows, transport processes, electrochemical step

Recent advances in understanding metal dusting: A review

Abstract: Recent experimental investigations have widened the understanding of metal dusting significantly. Microscopic observations have been used to dissect dusting mechanisms. Iron dusts by growing a cementite surface scale, which catalyses graphite nucleation and growth. The resulting volume expansion leads to cementite disintegration. Cementite formation on iron can be suppressed by alloying with germanium. Nonetheless, dusting occurs via the direct growth of graphite into the metal, producing nanoparticles offerrite.This process is faster, because carbon diffusion is more rapid in α-Fe than in Fe 3 C. Austenitic materials cannot form cementite, and dust via formation of graphite at external surfaces and interior grain boundaries. The coke deposit consists of carbon nanotubes with austenite particles at their tips, or graphite particles encapsulating austenite. TEM studies demonstrate the inward growth of graphite within the metal interior. It is therefore concluded that the dusting mechanism of austenitic materials like high alloy Cr-Ni steels and Ni base materials is one of graphite nucleation and growth within the near surface metal. In all alloys examined, both ferritic and austenitic, the principal mass transfer process is inward diffusion of carbon. Alloying iron with nickel leads to a transformation from one mechanism with carbide formation to the other without. Copper alloying in nickel and high nickel content stainless steels strongly suppresses graphite nucleation, as does also an intermetallic Ni-Sn phase, thereby reducing greatly the overall dusting rate. A surface layer of intermetallic Ni-Sn Fe-base materials facilitates the formation of a Fe 3 SnC surface scale which also prevents coking and metal dusting. Current understanding of the roles of temperature, gas composition and surface oxides on dusting rates are summarised. Finally, protection against metal dusting by coatings is discussed in terms of their effects on catalysis of carbon deposition, and on protective oxide formation.