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
2 13 14 15 16 17
2
3
4
5
6
7
8
9
10
11
12
3 4 5 6 7 8 9 10 11 12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
positive impact
low toxicity
medium toxicity
heigh toxicity
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103