Reforming liquid phase

Jongerius AL, Bruijnincx PCA, Weckhuysen BM (2013) Liquid-phase reforming and hydrodeoxygenation as a two-step route to aromatics from lignin. Green Chem 15 3049... 

Jongerius AL, Copeland JR, Foo GS, Hofmann JP, Bruijnincx PCA, Sievers C, Weckhuysen BM (2013) Stability of Pt/y-Al203 catalysts in lignin and lignin model compound solutions under liquid phase reforming reaction conditions. ACS Catal 3 464... 

Aqueous phase (or liquid phase) reforming is a new approach for converting biomass feedstocks into oxygenated speeies in the presence of water, and then subsequently converting the oxygenates into H2, syngas, or alkanes with the aid of catalysts in the aqueous phase (eqn (7.4)). This approach was pioneered by Dumesic and co-workers in 2002. Sinee then, this approach has been used to convert biomass feed stoeks into a variety of liquid fuels and chemicals. ... 

The liquid phase reforming by Dumesic et al. solves the problem by extracting oxygen as carbon dioxide, but then making hydrogen (Equation 1.15). 

Bimetallic catalysts have been the subject of great interest for a long time because of their exceptional properties compared to the monometallic catalysts, yet the reason behind their improved activity is still a question of debate and they are subject of many recent studies. Tanskale et al. [39] have studied the promoting effect of Pt and Pd in bimetallic Ni-Pt and Ni-Pd catalysts supported on alumina nanofibre (Alnf) for the liquid phase reforming of sorbitol to produce hydrogen. Fig. 4.19 shows TPD profiles for CO desorption for several monometallic and bimetallic catalysts dispersed on alumina nanofibre. 

The CO adsorption microcalorimetry was also used to explain the promoting effect of Pt in bimetallic Ni-Pt catalysts supported on alumina nano-flbre (Alnf) tested for the liquid phase reforming of sorbitol to produce hydrogen [51]. The differential heat of adsorption for Ni-Pt/Alnf reduced to around 111 kJ/mol, which was 12 and... 

The illustrated unit can be used to study vapor-phase reforming of kerosene fractions to high octane gasoline, or hydrogenation of benzene, neat or in gasoline mixtures to cyclohexane and methylcyclopentane. In liquid phase experiments hydrotreating of distillate fractions can be studied. The so-called Solvent Methanol Process was studied in the liquid phase, where the liquid feed was a solvent only, a white oil fraction. 

At least one developer is developing a liquid-phase fuel desulfurizer cartridge that will be used to remove sulfur prior to fuel vaporization. Other developers remove the sulfur immediately after vaporization and prior to the reforming. Hydrogen needs to be recirculated to the removal device to convert the sulfur species to H2S so that it can be entrapped on zinc oxide, a complication. 

The liquid phase adsorption processes for aromatics extraction are made economically relevant by the large world demand for aromatic petrochemicals. The global per annum production rates of the highest capacity aromatic petrochemicals derived from reformate or pygas for the recent past are shown in Table 7.1. 

An alternative approach for the utilization of biomass resources for energy applications is the production of dean-buming liquid fuels. In this respect, current technologies to produce liquid fuels from biomass are typically multi-step and energy-intensive processes. Aqueous phase reforming of sorbitol can be tailored to produce selectively a clean stream of heavier alkanes consisting primarily of butane, pentane and hexane. The conversion of sorbitol to alkanes plus CO2 and water is an exothermic process that retains approximately 95% of the heating value and only 30% of the mass of the biomass-derived reactant [278]. 

Aqueous phase reforming of glycerol in several studies by Dumesic and co-workers has been reported [270, 275, 277, 282, 289, 292, 294, 319]. The first catalysts that they reported were platinum-based materials which operate at relatively moderate temperatures (220-280 °C) and pressures that prevent steam formation. Catalyst performances are stable for a long period. The gas stream contains low levels of CO, while the major reaction intermediates detected in the liquid phase include ethanol, 1,2-pro-panediol, methanol, 1-propanol, propionic acid, acetone, propionaldehyde and lactic acid. Novel tin-promoted Raney nickel catalysts were subsequently developed. The catalytic performance of these non-precious metal catalysts is comparable to that of more costly platinum-based systems for the production of hydrogen from glycerol. 

The reactor can operate with either a liquid-phase reaction or a gas-phase reaction. In both types, temperature is very important. With a gas-phase reaction, the operating pressure is also a critical design variable because the kinetic reaction rates in most gas-phase reactions depend on partial pressures of reactants and products. For example, in ammonia synthesis (N2 + 3H2 O 2NH3), the gas-phase reactor is operated at high pressure because of LeChatelier s principle, namely that reactions with a net decrease in moles should be mn at high pressure. The same principle leads to the conclusion that the steam-methane reforming reaction to form synthesis gas (CH4 + H20 O CO + 3 H2) should be conducted at low pressure. 

In practice catalytic reforming is usually carried out in fixed bed reactors (see Fig. 2.2). Because the reactions are endothermic, heat has to be introduced. A conventional scheme is based upon a series of three or four adiabatic fixed bed reactors with interstage heating. Part of the hydrogen produced is recycled to maintain high hydrogen partial pressures. The product mixture from the last reactor is cooled and separated into a gas phase and a liquid phase. The latter is purified by distillation. 

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