Hydrogen separation process

Pressure swing adsorption cycle sequence for a four-bed system. (Adapted from Miller, G.Q. and Stocker,., Selection of a Hydrogen Separation Process, UOP Report, January 1999, available at http //www.uop.com/ objects/SelOfHydroSepProc.pdf Cassidy, R.T., Adsorption and ion exchange with synthetic zeolites, in ACS Symposium Series, ed. W.H. Flank, American Chemical Society, Washington, Vol. 135, p. 275,1980.)... 

Flytzani-Stephanopoulos, M., X. Qi, and S. Kronewitter, Water-Gas Shift with Integrated Hydrogen Separation Process, Final Report, U.S. DOE Contract DE-FG2600-NT-40819, February 2004. 

Polymer membranes are the most common commercial membranes for separations [1]. They have proven to operate successfully in many gas and liquid separations. For example, polymer membrane-based gas separation processes have undergone a major evolution since the introduction of the first polymer membrane-based industrial hydrogen separation process about two decades ago. The... 

TABLE II, ADVANTAGEOUS FEATURES OF HYDRIDE-HYDROGEN SEPARATION PROCESSES... 

A proprietary hydrogen separation process utilizing the reversible and selective adsorption capability of mixed metal hydrides has been proposed. The hydride, forming compounds, such as LaNi5, FeTi, or Mg2Cu, are in the form of ballasted pellets. 

Miller, G.Q. and Stocker, J. Selection of a hydrogen separation process. 1999. http //www.uop. com/objects/SelOfHydroSepProc.pdf (accessed October 15, 2005). 

Geoffrey Q. Miller and Joerg Stoecker, Selection of a Hydrogen Separation Process, 1989 NPRA Annual Meeting, March 19-21, 1989, p. 26. 

There are, of course, other limiting situations that may be considered, for example if protons are compensated by negative point defects such as metal vacancies or oxygen interstitials. These are, however, mainly dominant under oxidizing conditions, not commonly considered for hydrogen-separation processes. 

G. Q. Miller, J. Stocker, Selection of a hydrogen separation process, 4th European Technical Seminar on Hydrogen Plants, Lisbon (Portugal), Oct 2003. 

Palladium or its alloys are the most practical membrane materials, due to their high hydrogen permeability and stability at high temperatures. The membrane reformer is composed of a steam reformer equipped with palladium-based alloy modules in its catalyst bed, and can perform steam reforming reaction and hydrogen separation processes concurrently with no help from shift converter and PSA, as shown in Fig. 12.1. 

A conventional ATR plant is represented in Figure 3.1, which includes the following steps reformer, a shift reactor (WGS), and hydrogen separation process (Liu et al., 2010). 

Although the development of new metals as alternatives to Pd in hydrogen separation membranes is very promising, many aspects concerning the stability and reliability of these innovative membranes have yet to be defined. The main problems to be solved are embrittlement under hydrogenation cycles and permeance/selectivity performances appropriate to the hydrogen separation processes of practical interest. Therefore, only a few application studies are reported here. 

Abstract Dense ceramic membrane reactors are made from composite oxides, usually having perovskite or fluorite structure with appreciable mixed ionic (oxygen ion and/or proton) and electronic conductivity. They combine the oxygen or hydrogen separation process with the catalytic reactions into a single step at elevated temperatures (>700°C), leading to significantly improved yields, simplified production processes and reduced capital costs. This chapter mainly describes the principles of various types of dense ceramic membrane reactors, and the fabrication of the membranes and membrane reactors. 

Several techniques can be used for H2 separation from mixtures with other gases, as shown in Table 12.2. Nevertheless, pressure swing adsorption (PSA), cryogenic distillation and membrane separation techniques are the main hydrogen separation processes (Adhikari and Fernando, 2006). 

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