LaRuSi for ammonia synthesis

16 December 2018 - Chemical Zoo

larusi2018.PNGAmmonia synthesis with electrides update. In 2012 Kitano et al. used a ruthenium doped Ca/Al/O zeolite (previous report) and in 2018 the catalyst of choice is La/Ru/Si (DOI).

Synthesis: combine elemental lanthanum, ruthenium and silicon by arc welding, repeat melting 5 times and anneal at 1000 degrees for 2 weeks. Key difference with the 2012 iteration: ruthenium nanoparticles on an electride support tend to clutter together with rapidly diminishing activity whereas the 2018 iteration is a intermetallic compound: an alloy but with a defined crystal structure. In this structure the La atoms form a distinct layer alternating with layers of Ru/Si atoms. Also accounted for are pseudo atom sites, the location of the anionic electrons. Hydrogenation is easy: there is room for one hydrogen atom in every La4 unit. Maximum ammonia production in a hydrogen/ nitrogen stream: 1760 micromole per gram per hour. For comparison, CaRuSi did nothing, as did LaCoSi (another 2018 iteration). The 2017 iteration LaScSi was not compared.

As for a mechanism ammonia synthesis works by hydrogenation, hydride exchange with the anionic electrons, followed by nitrogen adsorption and dissociation by a hot atom mechanism.

Mob infiltrates chemistry faculties

01 December 2018 - News

Small news bit to be filed in the section "Dutch illegal drugs trade". (latest episode here) According to the mayor of the Dutch town of Westervoorde the mob is infiltrating schools and universities with the aim to recruit chemistry students for a "career" in illegal drug laboratories. (NOS news). It has prompted him to consider preparing course material for students to educate them on the dangers of getting involved with criminals. And he is serious about this: his province has 125,000 students and they are recruited "on a large scale" as drug couriers and also partly as producers.

Crime site crimesite.nl is sceptical. (link) How many students actually find employ in this industry? They asked one of the chemistry student bodies but they do not know of any incident involving one of their members.

Reminds me of a infamous case of 25 years ago where a DSM employee was caught moon lighting as a analytical chemist for the local drug cartel. What makes that case remarkable is that this guy was that good the company took him back after he had served his sentence.

Rik

PS You have to understand Dutch to appreciate this one but the NOS site mentions "scheikunde" AND "chemie" students as if you can choose which degree to pursue. In fact both terms are synonymous, the older term "scheikunde" meaning "the art of separation".