Catalysis 2026 Issue

installed, its operating severity may need to be increased. In addition, high-sulphur feeds will increase SOx emissions; therefore, preventative measures may need to be taken if the FCC is operating against environmental limits. It can also increase H₂S loading in the fuel gas, which may require operational adjustments to the gas treating system. Nitrogen, when present as basic nitrogen, acts as a tem- porary poison for FCC catalyst by affecting active sites on the catalyst in the riser. Hence, an increase in nitrogen content in FCC feed can adversely impact product yields and conversion. High nitrogen can also impact NOx emis- sions. However, the impact of nitrogen on product quality is negligible. An increase in fresh catalyst dosing rate may be considered to address the impact of high basic nitrogen effects on the catalyst activity. Contaminant metals such as Ni, V, Na, and Fe have a major impact on product yields, conversion, and catalyst quality in the FCC unit, whereas contaminants such as chlorine (Cl) have a major impact on the operability of the main fraction- ator. Catalyst technology plays a major role in dealing with these metallic contaminants, as well as chlorides. Nickel is a well-known hydrogenation catalyst and widely used for hydrotreating applications. However, under typical FCC conditions (low pressures and high temperatures), it behaves as a dehydrogenation catalyst, promoting hydro- gen formation (higher dry gas) and coke via the mechanism shown in Figure 2 . An immediate operational handle to control the dry gas increase due to nickel is to reduce reactor severity by low- ering the reactor outlet temperature (ROT). However, lower ROT has an adverse impact on product yields and conver- sion, and thus on FCC economics. Some refiners also con - sider the injection of nickel passivator chemicals (such as antimony-based compounds) into the feed stream, which has its own advantages and disadvantages. A common approach to tackling nickel impact is to use Ni-trapping specialty alumina in the catalyst formulations. The effectiveness of nickel traps depends on the type of alu- mina used and its dispersion characteristics, among other factors. Since the nickel deposited on the catalyst is immo- bile, the effectiveness of nickel traps is limited. However, a novel approach for nickel passivation, called Boron-Based Technology (BBT), can be used. High nickel passivation efficiency, especially in very high nickel environments, has

H/CH ratio

Coke yield

0.6

34% increase

19% increase

0.5

0.4

0.3

0.2

0.1

Control

Chloride exposure

Control

Chloride exposure

been demonstrated using BBT technology, due to boron’s mobility in the FCC environment. Table 1 shows a suc- cessful application of the BBT-based proprietary Borocat catalyst in an Asian refinery trial, which processed high Ni feedstock to deposit more than 10,000 ppm-wt nickel on Ecat. Borocat catalyst not only reduced the dry gas and coke yields, but also increased the yields of other valuable products.3 Nickel gradually deactivates over time due to oxidation to NiO in the regenerator environment (to the +2 oxidation state). However, the presence of chlorides, either present in the feed or the fresh catalyst itself, can reduce nickel species back to their Ni (0) oxidation state, promoting its reactivation, as shown in Figure 3 .2 In addition, chlorides entering the FCC unit, either from the feed or fresh catalyst, can cause ammonium chloride deposits, leading to higher pressure drop, corrosion, and fouling in the main fractionator overhead system. Hence, using catalysts containing minimum or no chlorides helps minimise nickel reactivation, corrosion, and fouling. FCC catalysts produced using the in situ manufacturing method do not use chloride-based binders, which are normally required in the conventional incorporated catalyst manu - facturing process. These kinds of catalysts may also allow the processing of feeds with relatively higher chloride con- tent (such as pyoil derived from PVC waste). Figure 3 Effect of chloride on H₂ and coke yields due to nickel reactivation

Borotec Borotec Valor

3000

4000

5000

6000

7000

8000

V + Na (ppm-wt)

Olens additive

Figure 4 Ecat (left) and plant data (right) of a catalyst using Valor V-trap technology to process a high vanadium feed⁴

Catalysis 2026