Effect of Carbon Supports on Pd Catalyst for Hydrogenation Debenzylation of Hexabenzylhexaazaisowurtzitane (HBIW)

Research Progress and Key Issues of Hydrodebenzylation of Hexabenzylhexaazaisowurtzitane (HBIW) in the Synthesis of High Energy Density Material Hexanitrohexaazaisowurtzitane (HNIW)

“…They proposed that if the four oxygen atoms in the 797 # molecule were replaced by four nitramine groups, the resulting compound, 2,4,6,8,10,12-hexanitro-2,4,6,8,10,12-hexaazaisowurtzitane (5.5.0.0 5,9 .0 3,11 ) (HNIW, known as CL-20), would have more comprehensive performances than HMX does, and would become a new-generation HEDM. As can be seen in Figure 2, two five-membered rings connecting four N-NO 2 groups and a six-membered ring connecting two N-NO 2 groups together make up the complicated molecular structure of HNIW, where the fist two rings are connected by a C-C bond that has high tension in the polycyclic caged organic compound [1,6]. Professor Yu successfully synthesized this three-dimensional caged structure, CL-20, in 1994 [7].…”

“…Catalyst development. It has taken several decades for researchers to develop Pd/C catalysts as the key for the hydrogenation debenzylation of HBIW [6]. In 1997, Nielsen and Barbara succeeded in synthesizing TADBIW, and they only used 20 wt.% Pearlman's Pd/C catalyst and nearly the same amounts of HBIW.…”

“…In 1997, Nielsen and Barbara succeeded in synthesizing TADBIW, and they only used 20 wt.% Pearlman's Pd/C catalyst and nearly the same amounts of HBIW. Based on their works, scientists have investigated numerous Pd/C catalysts for commerce, which have significantly increased the catalytic activity [6]. In 1997, Wardle revealed that Degussa E101 NE/W had yields reaching 90% for hydrogenating HBIW when keeping the scale in a 50-g process, and with help from bromobenzene.…”

“…It was reported that in the chemical process, ACROS organic active carbon over a Pd catalyst performed better than other types of activated carbons [17]. Disordered mesoporous carbon (MC) had a yield of TADBIW as high as 80%, a very good catalytic reactivity, when it was prepared using the hard template method [6], while the yield of the prepared Pd(OH) 2 /MC catalyst, as a comparison, remained above 70% after two cycles. The researchers found that it is hard to obtain the target product when loading Pd with a concentration lower than 5 wt.% if the usage amount of the catalysts remains constant [17].…”

“…In 1995, Bellamy published a research report [29] on the preparation of TADBIW from HBIW by hydrodebenzylation-acetylation, pointing out that the yield of the product had been improved by appropriately increasing the reaction temperature, prolonging the reaction time, or increasing the amount of catalyst, i.e., Pd(OH) 2 /C. It concluded that direct nitration TADBIW produced high-yield CL-20, but the specific nitration medium and related process conditions were not provided [6,29]. Since TADBIW can be obtained by hydrodebenzylation only once, many countries and institutes initially adopted the one-pot nitration route for the synthesis of CL-20 [30][31][32][33], which is easy to realize at the laboratory scale.…”