Waste from paper and pulp industry sup­plies raw mater­i­al for devel­op­ment of new redox flow batteries

With the increas­ing use of renew­able ener­gies, sta­bil­iz­ing elec­tri­city net­works is becom­ing an ever great­er chal­lenge. Redox flow bat­ter­ies could rep­res­ent a major con­tri­bu­tion to solv­ing this prob­lem. Research­ers at Johannes Guten­berg Uni­ver­sity Mainz (JGU) are par­ti­cip­at­ing in a joint pro­ject that aims to devel­op new elec­tro­lytes for redox flow bat­ter­ies based on lignin, which is a waste product of the wood pulp man­u­fac­tur­ing pro­cess. The Mainz-based team of chem­ists and their part­ners in industry and the aca­dem­ic world are thus work­ing towards identi­fy­ing renew­able raw mater­i­als that will allow a more effi­cient gen­er­a­tion of sus­tain­able ener­gies. To date, the met­al vana­dium has been mainly used in flow bat­ter­ies but its avail­ab­il­ity is lim­ited and it is also expens­ive. For Pro­fess­or Siegfried Waldvogel’s team at the JGU Insti­tute of Organ­ic Chem­istry, this pro­ject provides them with access to a new research field in which they can bring to bear their many years of expert­ise in the sec­tor of electrochemistry. The aim of the research­ers is to pro­duce suit­able redox pairs that can be used in redox flow bat­ter­ies from lignin, the sub­stance that provides for sta­bil­ity in wood and plants in gen­er­al. These redox pairs are charged in the elec­tro­lyte of flow bat­ter­ies and are then stored in sep­ar­ate tanks. When required, they are sub­sequently recom­bined in a gal­van­ic cell to gen­er­ate energy. ​“By sub­ject­ing the waste sludge from paper and pulp pro­duc­tion to elec­tro­chem­ic­al decom­pos­i­tion we can obtain quinones, which we can then fur­ther pro­cess so they are suit­able for use in organ­ic bat­ter­ies,” explained Wald­vo­gel. The pro­ject is being fun­ded by the Ger­man Fed­er­al Min­istry of Food and Agri­cul­ture to Janu­ary 2019.

Elec­tro­syn­thes­is makes green chem­istry more viable

​“We are pla­cing increas­ing emphas­is on elec­tro­syn­thes­is here in Mainz,” added Wald­vo­gel, who has been work­ing on firmly estab­lish­ing this field of research at Johannes Guten­berg Uni­ver­sity Mainz since 2010. Over the last three years, his team has attrac­ted some EUR 4 mil­lion of fund­ing for new pro­jects in this field. In sim­pli­fied terms, elec­tro­syn­thes­is involves the use of elec­tric­al cur­rent as a kind of reagent, whereby the cor­res­pond­ing elec­trons are employed for the oxid­a­tion or reduc­tion of organ­ic sub­stances. This pro­cess is cheap­er and more envir­on­ment­ally friendly than the usage of con­ven­tion­al reagents assum­ing the elec­tri­city is gen­er­ated from renew­able resources. ​“The elec­tri­fic­a­tion of chem­ic­al syn­thes­is is cur­rently a really hot top­ic and the expect­a­tion is that this will revo­lu­tion­ize indus­tri­al pro­duc­tion world­wide in future,” Wald­vo­gel con­tin­ued. So far, only a few elec­tro­syn­thes­is-based tech­niques for syn­thes­iz­ing molecules on an indus­tri­al scale have proved prac­tic­able. One of the recent achieve­ments of Pro­fess­or Siegfried Waldvogel’s team is the devel­op­ment of a meth­od that makes it pos­sible to syn­thes­ize the fla­vor­ing agent vanil­lin from waste wood. In addi­tion, this tech­nique also enables the research­ers to gen­er­ate more rap­idly cer­tain adjuvant sub­stances that can be used for chem­ic­al reac­tions. One par­tic­u­lar suc­cess is a tech­nique developed in col­lab­or­a­tion with Novartis for the modi­fic­a­tion of a phar­ma­ceut­ic­al com­pon­ent: after con­ven­tion­al meth­ods proved inef­fect­ive, the research­ers in Mainz were able to gen­er­ate the product merely by means of elec­tro­chem­ic­al trans­form­a­tion. For Wald­vo­gel, the poten­tial of elec­tro­syn­thes­is goes bey­ond simply the pro­duc­tion of fla­vor­ing agents, fra­grances, and act­ive agents; he con­siders it can also be used to man­u­fac­ture spe­cial products for the agro­chem­ic­al industry as well as molecules that will be of interest to mater­i­als sci­ence. Thanks to the tech­nique, it is often pos­sible to abridge many of the phases of con­ven­tion­al syn­thes­is pro­cesses. In addi­tion, the meth­od reduces depend­ence on scarce raw mater­i­als that are usu­ally required to pro­duce the neces­sary chem­ic­al reagents. The pro­to­types of the flow elec­tro­lyz­ers employed in the team’s labor­at­ory for elec­tro­chem­ic­al reac­tions were designed and con­struc­ted in JGU’s own work­shop. Source: idw/​JGU