Hydrogen optimized distributions

Distributed and community hydrogen To further the optimization and replication of green hydrogen within distributed and community energy systems 2010... 

Parker, N. (2007). Optimizing the Design of Biomass Hydrogen Supply Chains Using Real-World Spatial Distributions A Case Study Using California Rice Straw. Master s thesis. University of California, Davis. 

The aim of this section is to demonstrate that the feasibility of a distributed hydrogen system based on methane ATR is the result of a combination between optimized engineering (design and operation) and catalyst (formulation and support structures and geometry). 

Industrially relevant consecutive-competitive reaction schemes on metal catalysts were considered hydrogenation of citral, xylose and lactose. The first case study is relevant for perfumery industry, while the latter ones are used for the production of sweeteners. The catalysts deactivate during the process. The yields of the desired products are steered by mass transfer conditions and the concentration fronts move inside the particles due to catalyst deactivation. The reaction-deactivation-diffusion model was solved and the model was used to predict the behaviours of semi-batch reactors. Depending on the hydrogen concentration level on the catalyst surface, the product distribution can be steered towards isomerization or hydrogenation products. The tool developed in this work can be used for simulation and optimization of stirred tanks in laboratory and industrial scale. 

Throughout the previous discussions, HDS catalysts were described as containing two different types of catalytic sites, one that facilitates direct sulfur extraction and another that facilitates hydrogenation. This could easily be rationalized in catalysts of a few years ago wherein the distribution of the promoter in the catalyst surface was uncertain, the crystals of MoS2 were large, and the composition of the support was variable. However, as catalysts have been improved, the crystallite sizes have been reduced to as small as seven Mo atoms in a cluster, and the stoichiometry of promoter to Mo is optimized at 1/2. The surface of the support is now carefully controlled, and the stacking of MoS2 can be dictated with reasonable accuracy. With such improved catalysts, it now becomes difficult to surmise how two different types of sites can exist, each with a different composition and function. 

For optimal performance of dual function isomerization catalysts based on zeolite Y or mordenite, extensive removal of sodium is necessary. The finished catalyst must be highly crystalline, and the finely dispersed metallic hydrogenation function should be well distributed throughout the catalyst particles. The proposed mechanism explains the stabilizing influence on conversion and the suppression of cracking reactions by addition of the metallic hydrogenation function to the active acidic catalyst base. 

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