Catalyst Poisons

Poisonous contaminants derive usually from fuel, lube oil, urea solution or from silencers as described previously.
Not much is known about the effects in cases where more than one toxic compound is present.

However, some substances have been characterized and their adverse effects are better known. Two reasons most likely for loss of activity are: Firstly, by plugging the pores in the catalyst matrix the access to the active centers will be blocked for the reactants. Secondly, some compounds like e.g. alkali and alkali earth metal oxides may mask directly the active centers.

Please refer to the illustration of the periodic table of elements below for potentially toxic elements prevalence as well as for their effects on catalysts.

catalyst poisons indicated on the periodic table of the elements - list of all toxic elements for SCR catalysts - inactivation of catalysts - chemical properties of elements - abundancy of elements in the earth crust
23
Krypton
Weight [Atomic Mass Units]234,555
Density11,5
Melting Point [°K]23
Boiling Point [°K]200
Abundance in Earth Crust [ppm]12
Tolerance for HFO, Diesel & Natural gas [mg/kg]12
Tolerance for Biofuels [mg/kg]12

Table of Poisons for SCR Catalysts

1 18
1
H
 2 13 14 15 16 17
2
He
3
Li
4
Be
5
B
6
C
7
N
8
O
9
F
10
Ne
11
Na
12
Mg
 3 4 5 6 7 8 9 10 11 12
13
Al
14
Si
15
P
16
S
17
Cl
18
Ar
19
K
20
Ca
21
Sc
22
Ti
23
V
24
Cr
25
Mn
26
Fe
27
Co
28
Ni
29
Cu
30
Zn
31
Ga
32
Ge
33
As
34
Se
35
Br
36
Kr
37
Rb
38
Sr
39
Y
40
Zr
41
Nb
42
Mo
43
Tc
44
Ru
45
Rh
46
Pd
47
Ag
48
Cd
49
In
50
Sn
51
Sb
52
Te
53
I
54
Xe
55
Cs
56
Ba
72
Hf
73
Ta
74
W
75
Re
76
Os
77
Ir
78
Pt
79
Au
80
Hg
81
Tl
82
Pb
83
Bi
84
Po
85
At
86
Rn
87
Fr
88
Ra
104
Rf
105
Db
106
Sg
107
Bh
108
Hs
109
Mt
110
Ds
111
Rg
112
Cn
113
Uut
114
Uuq
115
Uup
116
Uuh
117
Uus
118
Uuo
positive impact
low toxicity
medium toxicity
heigh toxicity
57
La
58
Ce
59
Pr
60
Nd
61
Pm
62
Sm
63
Eu
64
Gd
65
Tb
66
Dy
67
Ho
68
Er
69
Tm
70
Yb
71
Lu
89
Ac
90
Th
91
Pa
92
U
93
Np
94
Pu
95
Am
96
Cm
97
Bk
98
Cf
99
Es
100
Fm
101
Md
102
No
103
Lr