Nitrogen capacity

The observed variation of nitrogen sorption capacity at atmospheric pressure with content of presorbed water is shown in Figure 2. In all cases, the nitrogen capacity is seen to fall off regularly with increasing amounts of presorbed water, the rate of fall being highest in zeolite NaA and lowest in zeolite NaY. 

Nitrogen capacities for pure gas were determined In a similar manner. Following activation, the adsorbent beds were allowed to equilibrate 1n a stream of dry nitrogen at 30°C. Thermal desorption coupled with void volume measurements by helium displacement into a gas buret at atmospheric pressure yielded the amount of nitrogen adsorbed. 

Table II. Nitrogen Capacity and Selectivity at 30°C and One Atmosphere Pressure for Selected Adsorbents...

A self-bound sample containing a mixture of LSX and A zeolite (sample 3) showed better N2 adsorption properties than the standard CaX adsorbents. Not only was the nitrogen capacity notably higher, but the N2/O2 selectivity was Improved even with the A zeolite present. This result was surprising considering that the A zeolite, having Inferior N2 adsorption properties, reduced the overall properties of the LSX adsorbent. 

It can be seen that world development is following the direct synthetic ammonia process and that this process is rapidly replacing the two older and more costly processes, the arc and cyanamide. It will shortly come about that to speak of the capacity or of the production by the direct synthetic ammonia process will be tantamount to speaking of fixed atmospheric nitrogen capacity or production. 

Global nitrogen capacity is projected to increase from 114.4 million tonnes in 1994/95 to 123.5 million tonnes in 2000 - at a rate of 2 million tpy. In contrast, Pz05 capacity is projected to increase by only 2.5 million tonnes. Tlie existing excess capacity does not make investment in new capacity profitable. Despite this small increase, no shortages of phosphate fertilizers are expected in the 1990s. Likewise, the existing excess pot-ash-capacity-may.lead-to. closure of some of the potash capacity - from 36.1 million tonnes in 1994/95 to 35.0 million tonnes in 2000. 

For water-rinsed and acid-leached rice husks. Fig. 13.11a, b shows lower nitrogen capacity and no apparent desorption hysteresis loop, indicating that the porosity of the two raw materials is relatively lower than that of heat-treated rice husks samples. For carbonized in nitrogen and burned in air atmosphere husk samples. Fig. 13.11c, d shows that the isotherms are of type 1 according lUPAC classification. The hysteresis loops (associated with capillary condensation) found in both samples are of various shapes. According to these observations, BRHA is mainly microporous with narrow pore size distribution while WRHA contains both micro- and mesopores. 

The N2/CH4 isotherms on Sr-ETS-4 that have been heat-treated at 315 °C are shown in Figure 10.49. The results are similar to those reported by Kuznicki et al. (2001). Comparing the N2 isotherms of Sr-ETS-4 and clinoptilolites, the capacity of the latter is substantially larger. Eor example, at 5 atm pressure, the nitrogen capacity of the purified clinoptilolite is nearly twice that of Sr-ETS-4. 

Nitrogen capacities in various parts of the world for 1975 and 1990 are given in Table... 

---