Attrition reforming

In a continuous reformer, some particulate and dust matter can be generated as the catalyst moves from reactor to reactor and is subject to attrition. However, due to catalyst design little attrition occurs, and the only outlet to the atmosphere is the regeneration vent, which is most often scrubbed with a caustic to prevent emission of hydrochloric acid (this also removes particulate matter). Emissions of carbon monoxide and hydrogen sulfide may occur during regeneration of catalyst. 

But most of the issues involve the catalyst system itself. The catalyst must be active and selective for the fuel of choice, stable, and resistant to poisoning and attrition while subjected to variations in flow, temperature, and pressure." For successful operation at commercial scale, the reforming process must be able to achieve high conversion of the hydrocarbon feedstock at high space velocities, as well as high H2 and CO selectivities. The reforming catalyst has to meet performance targets (see Table 1) as identified by U.S. DOE before it becomes feasible for use in the fuel reformers of transportation fuel cell... 

Fixed bed reactors still predominate for fuel processing. However, fixed beds are susceptible to vibrational and mechanical attrition. Recently, monolithic reactors, either metallic or ceramic, have attracted interest for reforming processes since they offer higher available active surface areas and better thermal conductivity than conventional fixed beds. Low-pressure drop and robustness of the structure are major advantages of monolithic reactors. 

However, the large number of centers flourished until healthcare reform (and associated cost containment) occurred in the late 1980s and 1990s, resulting in significant attrition among poison centers. Today there are only 69 PICs, 54 of which are AAPCC Certified Regional Poison Information Centers. 

Bio-oil reforming requires a multi-functional catalyst which can (1) steam reform the oil organic components into carbon dioxide (CO2), carbon monoxide (CO) and H2 (2) shift the produced CO with steam to make more CO2 and H2 (3) gasify carbonaceous residues formed on the catalyst surface mostly from non-volatile bio-oil components and (4) resist attrition. CoorsTek Ceramics produces spherical aluminas, with a range of physical properties, which could meet these requirements. Nickel-based catalysts, the most widely used shift... 

The mechanical strength of the fluidized catalyst is a significant process issue that must be solved. To address this operational problem, a two-step approach was taken to (1) identify and develop economical and attrition resistant support materials that could withstand high-temperature fluidization, and (2) prepare reforming catalysts from the best supports. The catalysts, containing nickel oxide (NiO), manganese oxide (MgO) and/or potassium oxide (K2O), were then evaluated for attrition resistance and activity in a fluid bed system. 

Eleven eommereial eatalysts were tested for attrition resistanee under simulated reforming eonditions. Two alumina supports supplied by CoorsTek Ceramies (90% and 99% alumina) showed the best eombination of attrition resistance and surface area. In addition, they eonsist of alpha... 

Most of the alumina materials tested exhibited improved attrition resistance under steam reforming conditions compared to that of commercial fluidized reforming catalysts though surface areas are about an order of magnitude less. 

Our approach was based on several observations 1) Although isolated cells remodel to only a limited degree when placed as a suspension into the midst of mature tissue without intrinsic organization, they will however reform appropriate tissue structure if proper conditions are provided. For example, manunary epithelial cells will form acini which secrete milk(19), and capillary endothelial cells tend to form tubular stmctures when placed on the properly adhesive substratum in vitro(20). 2) Tissues undergo constant remodeling due to attrition and remodeling of constituent cells. 3) Transplanted cells will survive only if implanted within a few hundred microns from the nearest capillary(21). 

Much research into biomass gasification in fluidized beds has concerned the use of dolomite [(Ca,Mg)C03] and olivine [(Mg,Fe)2Si04] as bed inventory. Of the two, olivine shows a slightly lower activity in biomass gasification and tar reforming, but has a higher attrition resistance than dolomite [73-75]. 

Catalysts for fluidized bed gasification of biomass should be efficient for the reforming of hydrocarbons and have high selectivity for syngas and high resistance to attrition and carbon deposition. They should also be relatively low cost, because the formation of ash and char necessitates the continual removal, and replenishment with fresh or regenerated material, of the bed inventory. In dual fluidized bed gasifiers, the inventory is also exposed to... 

Catalytic attrition and entrainment represent a problem in bubbling flui-dized-bed reactor, limiting the range of flow rate and dictates the use of cyclones. In the suggested fast fluidization (transport) reformer, the solid movement is exploited to the maximum limit in an integrated circulating configuration. 

The examination of the high temperature shift eatalyst is similar to that of the reforming catalyst. The eatalyst life for the high temperature shift catalyst is approximately 5 years. Pressure drop readings should be taken to cheek for possible catalyst attrition. The outlet composition should be validated with the expected composition with the design approach to equilibrium eonditions. 

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