The birth of DSA^® anodes

At the beginning of the 1930s, Oronzio De Nora had already produced more than a hundred plants. Following plants' success in producing sodium hypochlorite, chlorides of various types, and manganese dioxide, two new processes for the electrolysis of water and sodium chloride made with mercury cathode cells are emerging. From the electrolysis of water, oxygen, and hydrogen are produced. With hydrogen, a light gas, balloons are inflated; with oxygen, mainly oxyacetylene flame welding or flame produced by direct combustion with hydrogen is made. In the years leading up to World War II, the chlor-alkali production process was also developed, initially using mercury cathode cells. These early attempts would become the core of Oronzio De Nora's business in the postwar period. Chlorine, on the one hand, and caustic soda, on the other, would become the essential elements of entire production chains capable of generating multiple uses, from detergency to remediation, from manufacturing plastics to producing aluminum. From the postwar period onward, the index of chlorine and caustic soda production and consumption will be considered the benchmark for establishing a country's level of industrialization. 

With the war over, Oronzio De Nora is ready to test his first chlor-alkali cell. The prototype is installed at the Pirelli Group's Tolmezzo paper mill and has a 3000-ampere power supply. The beginning of it all happens almost by accident when Oronzio De Nora goes to the facilities of a factory in Lodi to inspect a malfunctioning plant, giving rise to frequent explosions. While defining the solution, Oronzio experiments with a construction variant, replacing the classic and cumbersome horizontal decomposer with a vertical decomposer that lets reagents circulate counter-currently and allows inspection of the cells from below. The solution quickly proved to be an essential innovation and began to be applied permanently in both De Nora and competitor plants.

A new headquarters is now needed, larger and more functional than the one in Via Arquà. Oronzio De Nora uses the old plant as a warehouse and starts constructing a new factory in Via Bistolfi. There will finally be room for a large and efficient research laboratory in the new location, then offices, workshops, and warehouses. Further refinement of the mercury cathode cell is also needed. Oronzio De Nora uses new materials and introduces a particular mercury cathode flow plane made of polished granite slabs instead of traditional concrete. De Nora's new mercury cathode cell is then completed with a very light and flexible vulcanized rubber cover, which allows automatic adjustment of the position of the anodes relative to that of the cathode, optimizing the system and allowing significant energy savings. From the early 1950s until the mid-1970s, De Nora's mercury cathode cell systems spread exceptionally rapidly, consistently proving the most reliable and effective. At that time, 40 percent of the world's chlorine production is made with De Nora technologies pulsing at the core of large-scale plants in Japan, America, Asia, and Europe.

The team led by Oronzio De Nora is working hard on innovations that could revolutionize the chlor-alkali process. To be profitably governed, electrolytic reactions must be framed within at least four basic parameters: how much energy they consume, what reaction rates they can produce, what degree of purity the final products exhibit, and, finally, how much they cost. Every chemical reaction to take place needs extra energy over and above what the theoretical model requires. Minimizing the passive resistances that result in this additional energy demand and thus cost is one of the research tasks. Through laboratory analysis, reaction rates and the quality of final products can also be affected, avoiding the costs directly or indirectly derived from the presence of waste materials to be eliminated. An idea takes shape in the mind of Oronzio De Nora to overcome the problems related to the fragility and consumption of graphite anodes, habitually used in industrial chlor-alkali cells. His idea is to experiment with a nondeteriorating metal anode capable of operating at low electrical voltages, minimizing passive energies, and allowing the transit of very high amounts of current. The new anode should then be able to develop higher reaction rates without generating parasitic side products; it should also be easily fabricated and recyclable, have low prices, and obviously, last a very long time.
From 1958 to 1965, the De Nora Group and Diamond Shamrock of Painesville, Ohio, developed a joint research program to bring these ambitious goals as close as possible. The studies initially target titanium as an ideal material for making new metal anodes. There was already a great deal of research highlighting how in the typical electrolyte of the chlor-alkali process, titanium immunizes itself to corrosion phenomena and even becomes an inert element, such that it does not allow current to flow. Oronzio De Nora's team is applying a thin film of platinum or platinum-iridium alloys to titanium anode structures, aiming to use titanium's ability to remain unaltered simultaneously and that of platinum and its alloys to stabilize the passage of even high currents. These anodes give good results in terms of reaction efficiency but are too expensive, even though platinum and its alloys are used in minimal quantities.

At some point, Oronzio and his brother Vittorio De Nora discover in Holland, in a small town on the border with Belgium, a small research laboratory consisting of two partners who, for different reasons, are working on the same problems. Henri Beer, one of the two partners, works full-time as a technician and financier of the small study. During the experiments on titanium coated with various platinum group metals, the two partners obtained a brown and compact coating, stable when used as an anode in chlor-alkali electrolysis and capable of flowing a high current impervious to corrosion phenomena. The De Nora research laboratory analyzes it and, after a series of complex chemical and structural analyses, discovers that it is ruthenium dioxide. To obtain that material, the two ingenious and fortunate Dutch researchers used a mixture of ruthenium and a special resin used by local fishermen to protect fishing boat hulls from the saltiness of the North Sea. The reaction of the two components generated a ruthenium compound known as resinate. The final mixture was applied as a varnish on titanium with a final heat treatment in the presence of air. During this final stage, the ruthenium resinate was decomposed with the formation of ruthenium dioxide, unbeknownst to the inventors, which proved to be an extraordinary catalyst for electrochemical reactions.
Through intensive research, the team led by Oronzio De Nora discovers that it is possible to obtain a complex oxide containing titanium dioxide and ruthenium dioxide by thermally decomposing a paint containing compounds of both elements simultaneously. The complex oxide is highly compatible with titanium bases, which anchor exceptionally well thanks to the titanium dioxide component. On the other hand, the catalytic activity for electrochemical reactions typical of pure ruthenium dioxide is also maintained virtually unaffected by the complex oxide. The titanium metal anodes, equipped with the special coating developed by De Nora and protected by the internationally registered trademark DSA®, take the company a prodigious leap forward in the quality and revolutionize the hitherto known standards in chlor-alkali production.

Oronzio De Nora once again mandates his brother to present the new product across the border. Vittorio sets out to conquer the world: his first stop is Japan, the kingdom of chlor-alkali. In just six months, the De Nora family put together seven major orders that will double the total chlor-alkali production in Japan. On the back of this success, the Permelec SpA company was founded, dedicated to manufacturing and marketing DSA® anodes. The technological revolution that De Nora's DSA® anodes have unleashed in the world of electrochemistry is accompanied by ingenious business insight. Permelec builds DSA® anodes but does not sell them to its customers; instead, it leases them for rent to be paid for each ton of chlorine produced. This innovative sales tactic enables approaching many new customers and overcoming initial misgivings about the surprising experimental results. Customers are reassured that they do not have to buy the anodes but only rent them and then return them without further charge: an aura of nobility begins to form around De Nora anodes that will characterize them for many decades. Graphite anodes were simple components of cells, and DSA®s became their heart: indispensable and irreplaceable elements in modern chlor-alkali production plants.

> Niccolò De Nora appears in the company